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Maternal Newborn Nursing

10.1 Physiologic Changes Due to Pregnancy

Maternal Newborn Nursing10.1 Physiologic Changes Due to Pregnancy

Learning Objectives

By the end of this section, you will be able to:

  • Explain physiologic changes due to pregnancy
  • Explain the functions of the placenta hormones
  • Differentiate between the presumptive, probable, and positive signs of pregnancy

Pregnancy affects every system in the pregnant person’s body. The changes begin at conception, support the pregnancy and the developing fetus, and prepare for labor. The reproductive and cardiovascular systems account for many of the physiologic changes of pregnancy. The placenta hormones, especially estrogen and progesterone, are responsible for initiating and supporting many physiologic changes of pregnancy.

Physiologic Changes

Nursing care during pregnancy requires the nurse to continually assess the pregnant person and to analyze the assessment data for expected versus unexpected cues. It is important for the nurse to understand the causes and manifestations of the anatomic and physiologic changes that occur during pregnancy in order to educate the pregnant person about them. The education provided by the nurse helps the pregnant person adapt to the expected changes and recognize any unexpected changes that may place the pregnancy at risk. Table 10.1 summarizes the expected changes and associated symptoms experienced during pregnancy.

System Changes during Pregnancy
Reproductive Cessation of menses
Increase in size of uterus
Increased contractility of uterus
Changes in breasts to prepare for lactation
Cervical engorgement and softening
Vaginal engorgement and elongation
Cardiovascular Decreased peripheral vascular resistance
Increase in blood volume
Increase in cardiac output and pulse
Decrease in blood pressure
Physiologic anemia of pregnancy
Displacement of heart to the left
Respiratory Diaphragm rises 4 cm
Change from abdominal to thoracic breathing
Increase in respiratory alkalosis
Tidal volume increases
Gastrointestinal Motility is slowed
Change in taste
Swollen gums
Nausea and vomiting
Heartburn and gastroesophageal reflux disease (GERD)
Renal and Urinary Dilation of renal pelvis and ureters
Increased glomerular filtration rate (GFR)
Increased blood flow to kidneys
Decrease in bladder tone
Faster excretion of drugs
Integumentary Hyperpigmentation: linea nigra and melasma
Striae gravidarum
Increase in acne
Increase in sweating and flushing
Pruritic urticarial papules and plaques of pregnancy (PUPPP)
Musculoskeletal Lordosis
Ligament relaxation
Change in center of gravity
Immune General reduction in immune function (to prevent pregnant person from physiologically rejecting the fetus)
Endocrine Production of pregnancy hormones
Maintain and support the pregnancy
Maintain pregnant person’s and fetal metabolism
Glucose regulation
Table 10.1 Summary of Expected Physiologic Changes in Pregnancy

Reproductive System

Many significant changes occur in the reproductive system during pregnancy. The uterus expands to accommodate the growing fetus, amniotic fluid, and placenta. Changes in the vagina and cervix allow for passage of the fetus to the extrauterine environment. The ovaries assist in maintaining the pregnancy until the placenta takes over. The breasts are prepared for lactation.


The uterus is a unique organ because it can enlarge (via hyperplasia and hypertrophy) without increasing the number of its cells. The initial uterine enlargement is stimulated by estrogen. The myometrial cells in the walls of the uterus stretch and thin as the fetus grows, the placenta enlarges, and the amniotic fluid increases. The uterine blood vessels enlarge as well, increasing the blood volume supporting the pregnancy, with the majority of the blood flow to the placenta. The nonpregnant uterus weighs about 60 g, enlarging to 1,000 to 1,200 g at 40 weeks of pregnancy. The fundus of the enlarging uterus is at the symphysis pubis by 12 weeks of gestation and reaches its highest point at the xiphoid process around 36 weeks of gestation. At the end of the pregnancy, the enlarged uterus has displaced the intestines, changed the shape of the rib cage, shifted the lungs, and changed the pregnant person’s center of gravity (Figure 10.2). The enlargement also leads to hypercontractility of the uterus, resulting in spontaneous, irregular, and painless uterine contractions known as Braxton Hicks contractions that occur throughout the pregnancy. Braxton Hicks contractions normally have no effect on the cervix until the final weeks of the pregnancy when the cervix begins to soften in preparation for labor.

A three-panel image showing a silhouette of a woman at three stages of gestation. Panel A shows gestation at 12 weeks. Panel B shows gestation at 24 weeks. Panel C shows gestation at 36 weeks.
Figure 10.2 Displacement of Intestines during Pregnancy (a) These illustrations depict uterine enlargement at 12 weeks of gestation, (b) 24 weeks of gestation, and (c) 36 weeks of gestation. As the uterus enlarges throughout the pregnancy, it grows out of the pelvis and into the abdomen. The enlargement pushes the intestines higher in the abdomen, changing the shape of the diaphragm. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0)


The cervix (Figure 10.3) is the lower 3 to 4 cm of the uterus and connects the uterus to the vagina. The cervix contains the opening, or os, of the uterus. During pregnancy, estrogen causes the cervix to enlarge and soften, and progesterone causes the endocervical glands to increase in number and enlarge. The glands produce more mucus, forming the mucus plug in the cervix. The mucus plug helps to keep bacteria out of the uterus, decreasing the chance of infection. In the first part of pregnancy, the connective tissue within the cervix strengthens to prevent a preterm birth. In the final 3 or 4 weeks, the connective tissue changes, becoming more elastic as labor approaches. Pregnancy hormones are responsible for changes in the connective tissue of the cervix (Pantelis et al., 2018).

Figure 10.3 Cervix The cervix is the neck of the uterus and connects the uterus to the vagina. The cervical os is the opening of the uterus. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0)


The vagina has both elastic and muscular characteristics. Estrogen causes an increase in vascularity, hypertrophy of the cells, and an increase in vaginal discharge during pregnancy. The increase in vaginal discharge and the decrease in the pH of the vagina protect the pregnancy from bacterial infections but raise the risk of candidiasis in the vagina. Relaxation and elongation of the vagina and perineum increase in preparation for birth.


Once the ovum is fertilized and starts dividing, the pre-embryonic cells stimulate the production of human chorionic gonadotropin (hCG), causing the corpus luteum to produce progesterone (see Figure 3.8). The progesterone secreted by the corpus luteum within the ovary helps to support the pregnancy. This hormone stimulates the growth of the endometrium needed for successful implantation until hormone production from the placenta takes over. The increase in estrogen and progesterone during pregnancy prevents ovulation by blocking secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The ovaries and fallopian tubes remain near the fundus of the uterus and become abdominal organs after the 14th week of gestation.


Changes in the breast are in preparation for breast-feeding the newborn. Estrogen and progesterone cause the breasts to enlarge, and the growth causes the breasts to be tender. The increase in vascularity of the breasts causes the veins to become more visible. The nipples and areola become more prominent, larger, and darker in color, and the sebaceous Montgomery glands secrete a lubricant to decrease cracking during breast-feeding. Alveolar cells begin producing colostrum between 12 and 16 weeks of gestation. Estrogen and progesterone suppress milk secretion during pregnancy.

Cardiovascular System

Many changes within the cardiovascular system support the pregnancy and fetal development. The changes begin with an increase in blood volume and cardiac output and simultaneous decrease in systemic vascular resistance starting early in the pregnancy. Physiologic anemia, hypercoagulation, and a slight enlargement of the heart are cardiovascular changes later in the pregnancy. All the cardiovascular changes prepare the pregnant person for events during pregnancy, labor, birth, and postpartum and are included in patient education.

Blood Volume

During pregnancy, the total blood volume increases 1,500 mL by 30 to 32 weeks of gestation. This is a 40 to 50 percent increase above the total blood volume of the nonpregnant person. Both the plasma volume and the number of red blood cells (RBCs) increase to support the uterine, placental, fetal, and pregnant person’s needs as the pregnancy progresses. The increase in plasma volume is proportionally higher than the increase in RBCs, causing hemodilution leading to a physiologic anemia of pregnancy. Table 10.2 lists the expected hematologic lab values during pregnancy.

Hematologic Lab Test Nonpregnant First Trimester Second Trimester Third Trimester
Hemoglobin (g/dL) 12–16 11.6–13.9 9.7–14.5 9.5–14.5
Hematocrit (%) 36–48 31.0–41.0 30.0–39.0 28.0–40.0
RBC (×106/mm3) 4.2–5.4 3.42–4.55 2.81–4.49 2.71–4.43
WBC (×106/mm3) 4.5–11 5.7–13.6 5.6–14.8 5.9–16.9
Table 10.2 Hematologic Lab Value Changes during Pregnancy RBC, red blood cell; WBC, white blood cell
(Cunningham, 2018)


The change in blood volume increases the pregnant person’s heart rate by 15 to 20 beats per minute. Cardiac output is also affected by the change in blood volume and increases 30 to 50 percent by 28 to 30 weeks of gestation. The increase in heart rate and cardiac output raises the stroke volume 25 to 30 percent during pregnancy. The increase in total blood volume also leads to the presence of a systolic murmur (Table 10.3).

Preconception Baseline First Trimester Second Trimester Third Trimester
Cardiac output ⇑⇑ ⇑⇑
Pulse ⇑⇑ ⇑⇑⇑
Blood pressure
Blood volume ⇑⇑ ⇑⇑⇑
Table 10.3 Effect of the Cardiovascular Physiologic Changes during Pregnancy on Cardiac Output, Pulse, Blood Pressure, and Blood Volume (Taranikanti, 2018)

Anatomically, the growing uterus causes the heart to shift upward and to the left (Figure 10.4). This shift requires slight modifications of the placement of the stethoscope when auscultating the heart.

An illustration of a woman’s thorax, ribs, and heart. It includes lines indicating how the diaphragm rises and displaces the heart to the left when pregnant.
Figure 10.4 Displacement of the Diaphragm and Heart during Pregnancy As the uterus enlarges during pregnancy, the diaphragm rises, and the heart is displaced to the left. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0)

Peripheral Vascular Resistance

The hormones progesterone and relaxin are responsible for the decrease in peripheral vascular resistance during pregnancy, which helps the pregnant person adapt to the increase in blood volume (Morton, 2021). The change in peripheral vascular resistance lowers blood pressure during pregnancy and, along with the increase in blood volume, also results in an increase in the pregnant person’s heart rate. The lowest blood pressures occur around 28 weeks of gestation, with a rise back to prepregnant values by the 36th week of pregnancy. The expected heart rate for a pregnant person is 60 to 120 beats per minute. The weight of the pregnant uterus in the final weeks of pregnancy increases the risk for varicosities and dependent edema in the lower extremities.


An increase in the ability of the blood to coagulate, or hypercoagulability, occurs during pregnancy to prepare the pregnant person for the normal blood loss during the process of birth and possible postpartum hemorrhage. Table 10.4 lists coagulation lab profiles. Plasma fibrin increases 40 percent, and fibrinogen increases 50 percent. The platelet count falls slightly because of hemodilution during pregnancy. The increase in blood coagulability, along with blood pooling from the weight of the uterus on the lower extremities, places the pregnant person at risk for venous thrombus formation.

Lab Test Nonpregnant First Trimester Second Trimester Third Trimester
Platelet count (×109/L) 150–450 174–391 155–409 146–429
PT (sec) 11–13.5 9.7–13.5 9.5–13.4 9.6–12.9
aPTT (sec) 25–-35 24.3–38.9 24.2–38.1 24.7–35.0
Fibrinogen (mg/dL) 200–400 244–510 291–538 373–619
Table 10.4 Coagulation Lab Value Changes during Pregnancy aPTT, activated partial thromboplastin time; PT, prothrombin time.
(Cunningham, 2018)

Respiratory System

The respiratory system changes both physiologically and anatomically during pregnancy. The physiologic changes are part of the modifications in metabolic needs of the pregnant person and developing fetus. The pregnant person’s metabolic rate rises up to 15 percent, increasing oxygen consumption by 20 percent. An increase in tidal volume (35 to 50 percent) and slight respiratory alkalosis facilitate the transport of carbon dioxide produced by the fetus. The rise in progesterone, estrogen, and prostaglandin production leads to nasal, sinus, and lung tissue congestion, resulting in a feeling of dyspnea and increasing the risk of nosebleeds in the pregnant person.

The anatomic changes are adjustments of the diaphragm to the growing uterus and the increase in diameter of the rib cage as the muscles and cartilage relax. The diaphragm rises about 4 cm, and the rib cage diameter enlarges about 6 cm. These anatomic modifications cause the pregnant person to change from abdominal breathing to thoracic breathing and are thought to be one cause of dyspnea during pregnancy. Explaining the physiologic and anatomic changes of the respiratory system during pregnancy is part of nursing care.

Gastrointestinal System

Many of the changes in the gastrointestinal system during pregnancy are due to the rise in progesterone levels slowing the motility of the entire gastrointestinal tract. Nausea, vomiting, and heartburn caused by the slowing of gastrointestinal motility are common symptoms during pregnancy. Hemorrhoids also may occur because of a combination of the relaxation of blood vessels in the rectum and the weight of the growing uterus. Cholelithiasis results from the slow emptying of the gallbladder caused by the increase in estrogen production during pregnancy. Extreme pruritis can be related to liver or gallbladder disease and requires further assessment.


Both progesterone and estrogen production change a pregnant person’s ability to taste and smell and have been linked to the cravings many pregnant persons experience. During pregnancy, an increase in the acidity of the saliva may cause a change in taste as well. Excessive salivation, or ptyalism, is linked to pregnant persons with nausea who are reluctant to swallow their saliva. Ptyalism can cause a constant bad taste in the mouth.

The rise in estrogen causes an increase in the vascularity of the gums. This predisposes the pregnant person to bleeding from the gums, gingivitis, and periodontal disease. The increase in the acidity of saliva is also linked to periodontal disease. Dental hygiene is an important topic of patient education throughout pregnancy.

Esophagus and Stomach

Because of the decrease in peristalsis, the esophagus and esophageal sphincter are more relaxed, and gastric emptying is slowed. The result is an increased incidence of heartburn and gastroesophageal reflux disease (GERD) during pregnancy. In the third trimester, the stomach is pushed up by the enlarging uterus, leading to a feeling of fullness and nausea in addition to dyspepsia and GERD. Sitting up for 30 to 60 minutes after eating helps to decrease the incidence of heartburn and acid reflux. Nutrition and over-the-counter relief measures for heartburn and acid reflux are included in patient education.


The slowing of the entire digestive system by the decrease in peristalsis during pregnancy allows more nutrients to be absorbed by the pregnant person as the process of digestion is completed. The increase in absorption is important to meet the nutritional needs of the pregnant person and the developing fetus. The consequence of reduced peristalsis increases the risk for constipation during pregnancy. Nursing care and education include balancing nutritional needs, activity, and gastrointestinal symptoms throughout the pregnancy.


The slowing of the digestive system also causes delay in emptying of the gallbladder. The accumulation of bile and the increase in serum cholesterol predispose the pregnant person to cholelithiasis and cholecystitis, with the highest incidence in pregnant persons 35 years of age or older. The nurse educates and encourages the pregnant person with gallbladder problems to maintain a low-fat diet to delay or avoid surgery whenever possible.


During pregnancy, the liver enlarges slightly to accommodate the increased demand for energy to support the pregnancy and the developing fetus. The liver is also essential in the detoxification of fetal metabolites entering the pregnant person’s bloodstream after crossing through the placenta. Physiologic changes in the liver include increased cholesterol synthesis and increased production of clotting factors. Cholesterol is needed for fetal growth and development and the production of estrogen and progesterone (Uvoh et al., 2021). The increase in clotting factors is needed to control bleeding after labor and birth and during the postpartum period. Physiologic changes in the liver during pregnancy also increase the incidence of spider angioma and palmar erythema. The increase in physiologic functions of the liver changes the nurse’s assessment of the liver in the pregnant person to include questions focusing on the symptoms of liver inflammation and deep vein thrombosis (DVT) and reviewing liver function tests when ordered by the health care provider. Changes in the physiologic function of the liver also require patient education focusing on recognition of the signs and symptoms of inflammation of the liver (nausea, fatigue, right upper quadrant discomfort, and jaundice).

Life-Stage Context

Age-Specific Gastrointestinal Concerns

Pregnant persons 35 years of age and older have an increased incidence of nausea and vomiting during pregnancy. The number of weeks nausea and vomiting persist in this population is greater than for those under 35 years old. The risk for excessive nausea and vomiting increases the incidence of treatment for dehydration with intravenous (IV) fluids, antiemetics, and the need for more than over-the-counter or home remedies.

Pregnant persons 35 years of age and older are also at increased risk for gallbladder disease during pregnancy. The need for surgery during pregnancy to remove the gallbladder is based on the severity of symptoms experienced by the pregnant person, the amount of blockage when cholelithiasis is present, and whether cholecystitis is present. The ability to perform a laparoscopic-assisted cholecystectomy is a consideration in whether to perform surgery during pregnancy or to wait until the postpartum period (Celaj & Kourkoumpetis, 2021).

Renal and Urinary System

Changes in the urinary system are in response to the anatomic and physiologic changes of pregnancy. There is a 50 percent increase in blood flow in the kidneys, dilating the renal pelvis and ureters. The glomerular filtration rate (GFR) rises along with an increase in urine volume during pregnancy. More solutes are filtered during pregnancy because the kidneys are now filtering waste products from both the pregnant person and the fetus. The increase in filtration of solutes overwhelms tubular reabsorption, and low levels of glucose and protein are excreted in the urine. The change in the GFR speeds up the excretion of drugs, and dosage adjustments must be made. For infections, a 7 to 10-day supply of antibiotics is usually prescribed during pregnancy instead of the 5-day supply in a person who is not pregnant. For anticonvulsants, serum levels need to be closely monitored and dosages modified, when needed, throughout the pregnancy to prevent a recurrence of seizure activity. Table 10.5 summarizes renal function lab changes.

Lab Test Nonpregnant First Trimester Second Trimester Third Trimester
BUN (mg/dL) 7–20 7–12 3–13 3–11
Serum creatinine (mg/dL) 0.6–1.1 0.4–0.7 0.4–0.8 0.4–0.9
GFR (mL/min) 90–120 131–166 135–170 117–182
Serum protein (g/dL) 6–8 6.2–7.6 5.7–6.9 5.6–6.7
Table 10.5 Renal Function Lab Value Changes during Pregnancy BUN, blood urea nitrogen; GFR, glomerular filtration rate.
(Cunningham, 2018)

Everyday activities involve a lot of sitting and standing. The weight of the uterus on the relaxed vascular system of the lower extremities causes pooling and edema, especially during the second half of the pregnancy. When the pregnant person lies on their side, the venous return is more efficient, and the pooling and edema are relieved, but the result is an increase in urine output, especially at night.

Bladder tone decreases, and capacity increases because of the rise in progesterone in pregnancy. Combined with the enlargement of the renal pelvis and ureter, the decrease in bladder tone allows for stasis of urine. The result is an increased risk for urinary tract infections during pregnancy. The increased incidence of hydronephrosis, urinary frequency, and urgency from the pressure of the uterus on the bladder often hides the symptoms of urinary infections during pregnancy.

The growing uterus tends to stay more toward one side of the pregnant person’s abdomen, putting pressure on that ureter and causing urine to build up in the kidney. Nurses can instruct the pregnant person to bend at the hips and support themselves on a table or sink (Figure 10.5). This pulls the growing uterus away from the maternal back, relieving pressure on the ureter and allowing the urine to flow into the bladder. This change in position also straightens the spine, relieving lower back ache.

All the anatomic and physiologic adaptations of the urinary system are discussed when the nurse provides patient education throughout the pregnancy. The education focuses on why the adaptations occur and how the pregnant person can prevent complications. A discussion on the possible need for medication adjustments is included as well.

A silhouette of a pregnant woman slightly bent forward at the waist, holding a table in front of her
Figure 10.5 Bending for Relief Bending at the waist with the feet at least a foot apart draws the uterus off the ureters, allowing urine to flow to the bladder. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0)

Integumentary System

During pregnancy, changes to the hair, nails, skin, sweat glands, and sebaceous glands are due to multiple physiologic increases in hormone production, cortisol levels, and metabolism. Once the pregnant person has given birth, the changes to the integumentary system fade or disappear. The process of fading or disappearing can be immediate or can take 2 to 3 months.


Estrogen, progesterone, and melanocyte-stimulating hormone are responsible for hyperpigmentation changes during pregnancy. In addition to the areola, there is a noticeable increase in skin pigmentation in two other places. The first is the linea nigra, a vertical line of increased pigmentation, which starts at the pubic hair line, passes through the umbilicus, and goes up to the xiphoid process (Figure 10.6). The second is melasma, the mask of pregnancy, or hyperpigmentation on the face from the cheekbones to the forehead. Both the linea nigra and melasma get darker in the sun, so the nurse advises the pregnant person to wear a hat and to cover the abdomen when spending time in the sun. Hyperpigmentation also occurs on the nipples, perineum, and axilla.

Images showing hyperpigmentation on the face and stomach. Image A shows a pregnant woman’s abdomen with hyperpigmentation in a line down the center. Image B is two images of a woman’s face with hyperpigmentation on the cheeks.
Figure 10.6 Hyperpigmentation during Pregnancy (a) The linea nigra is a vertical line of hyperpigmentation on the midline of the abdomen that is present during pregnancy. (b) Melasma is hyperpigmentation on the face that is present during pregnancy. (credit a: “March 13th” by Daniel Lobo/Flickr, CC BY 2.0; credit b: “what-is-melasma” and “causes-of-melasma” by Kylie Aquino/Flickr, Public Domain)

Striae Gravidarum

Stretch marks, or striae gravidarum, are reddish lines where the skin has stretched to accommodate the growth in the breasts, abdomen, and buttocks during pregnancy. Estrogen, relaxin, and adrenocorticoids affect the strength of the collagen within the skin, contributing to the formation of the striae (Figure 10.7). Applying lotions and creams to the skin during pregnancy has not been shown to decrease the occurrence of striae gravidarum, but these products can help to decrease itching.

A photograph of a pregnant abdomen with stretch marks scattered across the entire bottom portion. The lines appear as read marks.
Figure 10.7 Stretch Marks Striae gravidarum, or stretch marks, occur where the skin is stretched because of growth in the breasts, abdomen, and buttocks during pregnancy. (credit: Saildancer/pixabay, CC 0)

Acne and Sweating

The placenta plays a role in the increased production of androgens during pregnancy. Androgens influence the production of estrogen by the placenta (Parsons & Bouma, 2021). The increase in androgens during pregnancy contributes to the increase in acne on the face and upper body of the pregnant person. Androgens are also associated with oily skin and increased secretion from the sebaceous glands. Sweating and hot flushing occur more easily during pregnancy because of the increase in metabolism of the pregnant person.

Pruritic Urticarial Papules and Plaques of Pregnancy (PUPPP)

The benign skin condition of pregnancy called pruritic urticarial papules and plaques of pregnancy (PUPPP) is a rash made of a combination of hives, bumps, microvesicles, and plaques (Figure 10.8). PUPPP occurs most often in the first pregnancy. The rash starts on or near striae on the abdomen and can spread to the arms, legs, back, and buttocks. Lotions containing corticosteroids can help relieve the itching (American College of Obstetricians and Gynecologists [ACOG], 2022). The rash disappears shortly after giving birth.

A photograph of a pregnant abdomen with Pruritic Urticarial Papules and Plaques of Pregnancy. The PUPPP appears as rash-like red marks on both sides of the navel.
Figure 10.8 Pruritic Urticarial Papules and Plaques of Pregnancy PUPPP is a benign rash that occurs during pregnancy and consists of hives and plaques that itch constantly. (credit: “PUPPP” by Heykerriann/Wikimedia Commons, Public Domain)

Musculoskeletal System

Anatomic and mechanical changes occur in the musculoskeletal system during pregnancy. To facilitate vaginal birth, the ligaments of the pelvic joints stretch, increasing the inside diameters of the pelvis. However, relaxation of the ligaments is not confined to the pelvis because of systemic distribution of the progesterone and relaxin hormones. Patient education regarding changes in the musculoskeletal system includes relief measures for discomforts in the lower back, hips, and other joints, as well as ways to prevent injury.


Because of the weight of the pregnant uterus, the pregnant person’s center of gravity shifts, increasing the risk for falls. The posture of the pregnant person is also affected as the curvature of the spine changes and lordosis occurs to help correct the shift in the pregnant person’s center of gravity. Lordosis (Figure 10.9) and the weight of the pregnant uterus lead to lower back pain, especially in the later weeks of pregnancy.

A simple three-panel illustration of a pregnant woman showing her spine as it changes in curvature. The spine’s curvature increases as the pregnancy develops.
Figure 10.9 Lordosis Lordosis is a necessary anatomic adaptation of the spine in the pregnant person. (credit: modification of work from Anatomy and Physiology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0)

Role of Relaxin

During pregnancy, production of the hormone relaxin increases. Relaxin softens the ligaments in all joints in the body, and a change in posture and gait occurs. This is why pregnant persons should be instructed not to wear shoes with heels higher than 1 inch. Pregnant persons may also require minimal modifications to routine exercise regimens (ACOG, 2020a). If too much relaxin is produced, the symphysis pubis can separate, causing extreme pain and inability to walk. It takes several months after delivery for the symphysis ligaments to strengthen again.

Diastasis Recti

During pregnancy, the enlarging uterus stretches the abdominal muscles. For some pregnant persons, the stretching is significant enough to cause the connective tissue holding the muscles on each side of the abdomen to stretch and widen, forming a separation of the muscles, or diastasis recti (Figure 20.7). This leads to an increased risk for lower back pain during pregnancy. It takes several months of exercise after delivery to reduce the diastasis recti.

Immune System

Immunologic adaptations during pregnancy help to prevent the pregnant person’s body from rejecting the fetus. These changes also protect the fetus from infection. The result is that the pregnant person is more susceptible to some infections and the symptoms of some autoimmune disorders may worsen.

Endocrine System

Endocrine system adaptations are critical to maintain the health of the pregnant person, sustain the pregnancy, and promote the growth and development of the fetus. The functions of the pituitary, thyroid, parathyroid, and adrenal glands change as the pregnant person’s metabolism increases and the fetus grows and develops. The pituitary gland is responsible for the secretion of prolactin and oxytocin. Prolactin levels increase to promote breast development. Oxytocin levels increase slowly throughout the pregnancy in preparation for labor. The adrenal gland is responsible for the secretion of cortisol and aldosterone. The amount of cortisol produced by the adrenal gland does not increase, but the excretion of cortisol is delayed so that the serum level increases. Cortisol is necessary to maintain glucose levels. Aldosterone levels increase to help with fluid and electrolyte balance and blood pressure regulation.

The production of insulin in the pancreas alters in response to changes in carbohydrate metabolism to support the pregnancy and fetus. In the first half of the pregnancy, the pancreas is able to keep up with the insulin needs of the pregnant person. In the second half of the pregnancy, however, the human placenta lactogen hormone starts exerting an insulin resistance to meet the increased glucose needs of the fetus. The pregnant person must produce more insulin to maintain a normal glucose. If the pancreas is unable to produce an adequate supply of insulin, a sustained increase in blood glucose, or diabetogenic effect, occurs. This is why the nurse informs all pregnant persons who do not have pregestational diabetes that they will be tested for gestational diabetes during the second trimester.

Placenta Hormones

The hormones produced by the placenta are responsible for the establishment, progression, and maintenance of a pregnancy. The effects of the placenta hormones promote fetal growth and development. The placenta hormones that play a major role during pregnancy are human chorionic gonadotropin (hCG), progesterone, estrogen, human placental lactogen (hPL), and relaxin. The role of the placenta hormones in the physiologic adaptations of the pregnant person and fetal growth and development is summarized in Table 10.6. Patient education provided by the nurse explains the importance of the placenta hormones in supporting the pregnancy and fetal growth and development.

Hormone Function during Pregnancy
Human chorionic gonadotropin (hCG) Maintains the corpus luteum
Thickens the uterine lining
Stimulates the placenta to produce estrogen and progesterone
Human placental lactogen (hPL) Regulates the metabolism of the pregnant person
Increases glucose availability to the fetus
Helps to prepare the breasts for lactation
Estrogen Contributes to hyperpigmentation
Stimulates vascular relaxation
Helps to prepare the breasts for lactation
Increases vaginal discharge
Increases vascularity of the gums
Increases congestion in the nose and sinuses
Progesterone Prepares the uterus for implantation
Supports the fertilized egg prior to implantation
Contributes to hyperpigmentation
Stimulates vascular relaxation
Helps to prepare the breasts for lactation
Slows motility in the gastrointestinal system
Increases cervical mucus
Decreases bladder tone
Relaxin Softens the ligaments in all joints in the body
Helps to decrease peripheral vascular resistance in the pregnant person
Helps with cervical ripening and dilation
Table 10.6 Functions of the Placenta Hormones

Beta Human Chorionic Gonadotropin (hCG)

Human chorionic gonadotropin is produced as soon as the embryo’s trophoblast starts forming, leading to the development of the placenta. Serum levels of hCG peak at 10 weeks of pregnancy and continue to fall throughout the remainder of the pregnancy. The purpose of hCG is to support the pregnancy at the beginning by thickening the uterine lining and stimulating the placenta to produce estrogen and progesterone.

Human Placental Lactogen (hPL)

Human placental lactogen gradually increases throughout the pregnancy and peaks around 34 weeks of gestation. The purpose of hPL is to help regulate the metabolism of the pregnant person and increase the glucose available to the fetus. Human placental lactogen also helps prepare the breasts for lactation.


Estrogen helps to maintain the pregnancy by supporting the uterine lining and stimulating the growth of the uterus. Estrogen is also needed to help regulate many of the functions of the placenta. Estrogen helps to stimulate the development of the organs of the embryo.


Progesterone helps to prepare the uterus for implantation and to support the fertilized egg prior to implantation. Progesterone plays a major role in supporting the pregnancy after implantation as well. Many of the physiologic adaptations of the pregnant person occur because of progesterone.

Nutritional Needs

Adequate nutrition and calories are needed to promote the physiologic changes of the pregnant person and to support the pregnancy and the growth and development of the fetus. Increased intake of protein, folic acid, iron, and calcium helps the pregnant person meet the nutritional needs of pregnancy. (See the chapter on Prenatal Care for further discussion of nutritional needs during pregnancy.) The pregnant person requires 300 more calories per day and a minimum of eight glasses of water to promote the physiologic changes. Table 11.6 provides more detailed information on the nutritional needs of the pregnant person. Table 11.7 summarizes the expected trend in weight gain as the pregnancy progresses.

Food Groups

One-half cup of vegetables, 2 ounces of grains, or 1 ounce of protein—adding any of these to the daily basic needs of a nonpregnant person (based on age and height) will meet the daily nutritional needs of the pregnant person. The pregnant person should follow the guidelines set by the U.S. Department of Agriculture to meet the nutritional needs during pregnancy. The guidelines can be found at the website If eligible for the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), a pregnant person will receive nutrition counseling based on the guidelines.

Vitamins and Minerals

The recommended amounts of many vitamins and minerals also increase during pregnancy. In the first 8 weeks of the pregnancy, the rapidly developing embryo is totally dependent on the nutritional status of the pregnant person at conception and the continuing food intake throughout the pregnancy. Table 11.6 provides more detailed information on the vitamin and mineral requirements of the pregnant person.

Life-Stage Context

Age-Specific Nutritional Concerns

The diets of many teenagers in the United States have been found deficient in several micronutrients. This has been attributed to the high intake of fast food, convenience (often microwavable) foods, and high-calorie snack foods in the adolescent diet. The micronutrients include calcium, magnesium, iron, and vitamins D and E.

When a pregnant adolescent takes prenatal vitamins, they get sufficient iron and vitamin supplements. However, the adolescent’s calcium and magnesium intake is still inadequate. The continued deficiency of calcium may influence fetal bone growth. Magnesium deficiency has been associated with an increased risk of miscarriage, preterm birth, and fetal growth restriction.

The diets of pregnant persons 35 years of age and older who live in lower income households were also found to be deficient in the same micronutrients. The deficiencies were associated with an increased risk of miscarriage, preterm birth, and fetal growth restriction as well. Diet monitoring with reinforcement of adequate nutrition in both populations is an important nursing action throughout pregnancy.

Special Diets

A vegetarian consumes limited animal protein sources of nutrition, such as dairy products, eggs, and honey. A pescatarian prefers to consume only fish and seafood as animal sources of proteins. Vegans do not consume animal food sources or any food source produced by an animal, relying on plant-based foods to meet their nutritional needs. A well-balanced vegetarian, pescatarian, or vegan diet can supply the pregnant person with all the nutrients and calories needed during pregnancy. The nurse should assess the pregnant person’s current dietary intake to ensure that protein, calcium, iron, and vitamin B12 requirements are currently met. Patient education includes the following:

  • Soy, beans, lentils, and nuts are good alternative sources of protein.
  • Foods rich in vitamin C increase iron absorption.
  • Calcium-rich green leafy vegetables and tofu should be consumed.
  • A vitamin B12 supplement is essential.

In the United States, dairy products are a major source of calcium in the diet. When a person is lactose intolerant, the consumption of dairy products causes bloating, abdominal cramps, gas, and diarrhea. Plant-based sources of calcium include two cups of kale, mustard greens, or turnip greens; three-fourths of a cup of tofu; or one and one-half cups of white beans. These foods have the highest bioavailability of calcium in plant-based sources commonly consumed in the United States. Broccoli, kidney beans, and almonds also contain a significant amount of calcium. The nurse first assesses the knowledge of the pregnant person who is lactose intolerant regarding plant-based sources of calcium and educates them as needed.

The increase in knowledge regarding autoimmune intestinal diseases and gluten allergies has led to wider availability of gluten-free processed foods. However, some gluten-free foods have a higher fat and sodium content than gluten-containing options. Those who follow a gluten-free diet for medical reasons will be deficient in folic acid, vitamin B, iron, calcium, fiber, and grain servings. Vitamin and mineral supplementation becomes more important when balancing the needs of the pregnant person with intestinal symptoms and the needs of the developing fetus.

Influence of Culture on Diet

Certain foods are native to specific geographic areas, and others have been imported when people began trading and immigrating (Rasmussen et al., 2022). Children grow up eating the foods consumed by their parents and grandparents. The result is the development of food preferences, whether the preferences are nutritionally sound or increase the risk for obesity, hypertension, and diabetes. When a pregnant person completes a 72-hour nutrition diary, their food preferences and other dietary habits are often revealed. The nutrition diary is one way for the nurse to provide individualized nutritional counseling to people of a culture other than their own.

Awareness of the nutritional values of the foods and dishes of various cultures is needed to provide comprehensive nutritional counseling. Table 10.7 places common foods of populations based on geographic areas into the five basic food groups. Many of the foods are found in the traditional dishes for that geographic area.

Geographic Population Grains Vegetables Fruits Protein Sources Dairy
Native American Corn (maize)
Rice (Zizania)
Native fish
Mexican Corn (maiz)
Rice (arroz)
Sweet potatoes
Prickly pear
Beans (frijoles)
Eggs (huevos)
Deer (ciervo)
Chicken (pollo)
Beef (carne)
Fish (pez)
Goat (cabrito)
Shrimp (camarones)
Pork (carnitas)
Cow’s milk
South American Corn (maiz)
Rice (arroz)
Barley (cebada)
Wheat (trigo)
Sweet potatoes
Passion fruit
Pear (araza)
Acai berry
Black beans
Red beans
Cow’s milk
Goat’s milk
Southeast Asia Rice
(multiple varieties)
Lotus seeds
Banana flowers
Bamboo shoots
Dragon fruit
Majority of the population is lactose intolerant
Indian Barley
Potato (aloo)
Tomato (tamatar)
Okra (bhindi)
Cauliflower (phool gobhi)
Taro (arbi)
Eggplant (brinjal)
Water Buffalo milk
Cheese: paneer
Middle Eastern Rice
Camel’s milk/cheese
Goat’s milk/cheese
Table 10.7 Common Foods Consumed by Geographic Populations Placed within the Five Food Groups

Influence of Religious Practices on Nutrition

Religious practices may involve fasting on holy days, forbid the ingestion of specific foods and drinks, and specify rituals in food preparation. When a person is pregnant or breast-feeding, the fasting requirements are waived, but many pregnant persons elect to fast (Seiermann et al., 2021). The pregnant person needs to understand the importance of balanced nutritional practices every day to meet the needs of the developing and growing fetus. Food and drink restrictions are taken into consideration when the nurse provides dietary suggestions. Discussing food preparation rituals encourages a dialog about safe handling of food.


One significant concern for pregnant persons is a strong craving for and consumption of a nonfood substance, called pica. The top three ingested substances are dirt or clay, freezer ice or ice cubes, and laundry starch or corn starch. When a pregnant person consumes a nonfood substance, it replaces nutritional foods. Iron deficiency anemia can occur when a pregnant person consumes these nonfood substances. Pica occurs worldwide, but in the United States, the most common populations diagnosed with pica are pregnant persons and persons with intellectual disabilities (Hartmann et al., 2022). The physiologic cause is unknown.

Signs of Pregnancy

The physiologic and anatomic changes during pregnancy are the foundation of the presumptive, probable, and positive signs of pregnancy. The presumptive signs of pregnancy include the subjective cues of early pregnancy. The probable signs of pregnancy are composed of objective cues discoverable by the health care provider. The positive signs of pregnancy are cues provided by the fetus. The signs of pregnancy are summarized in Table 10.8.

Type of Sign Signs
Presumptive Amenorrhea
Nausea and vomiting
Urinary frequency
Breast enlargement and tenderness
Probable Chadwick sign
Goodell sign
Hegar sign
Enlargement of the uterus
Skin hyperpigmentation
Palpation of the fetus
Positive pregnancy test
Positive Auscultation of the fetal heart rate
Palpable fetal movement
Visualization of the embryo or fetus via ultrasound
Table 10.8 Signs of Pregnancy

Presumptive Signs of Pregnancy

The presumptive signs of pregnancy are symptoms noticed by the patient and include fatigue, urinary frequency, nausea and vomiting, amenorrhea, breast enlargement and tenderness, and quickening. Only quickening is unique to pregnancy. Amenorrhea can occur because of thyroid dysfunction, stress, morbid obesity, anorexia and malnutrition, and polycystic ovary syndrome (PCOS). In pregnancy, amenorrhea is caused by progesterone. Nausea and vomiting are symptoms of the flu, gastroenteritis, and intestinal blockage. Human chorionic gonadotropin (hCG) is the most likely cause of the nausea and vomiting of pregnancy. Fatigue can be due to anemia, lack of sleep, and cancer. Progesterone and lower blood glucose levels are associated with fatigue during pregnancy. Urinary frequency is a symptom of a bladder infection, pyelonephritis, and interstitial cystitis. The pressure of the growing uterus is the cause of urinary frequency in a person who is pregnant. Breast enlargement and tenderness are associated with increased prolactin levels or a breast mass. During pregnancy, the breasts enlarge as part of preparation for lactation. The perception of fetal movement by the pregnant person, or quickening, could be intestinal gas or associated with diarrhea. The presumptive signs are the least reliable symptoms confirming a pregnancy because the signs can also occur with other medical conditions.

Probable Signs of Pregnancy

Most of the probable signs of pregnancy are objective cues occurring during pregnancy. These signs are noticed by the provider and include Chadwick sign, Goodell sign, Hegar sign, enlargement of the uterus, skin hyperpigmentation, and palpation of the fetus. Chadwick sign is the bluish discoloration of the vagina and cervix due to the vasocongestion needed to support the growing uterus during pregnancy. Persons with endometriosis and adenomyosis will also exhibit Chadwick sign. Goodell sign is the softening of the cervix and vagina and the increase in vaginal mucus discharge during pregnancy. Hegar sign is the softening of the lower uterine segment during pregnancy. Connective tissue disorders can cause the cervix and lower uterine segment to soften.

Enlargement of the uterus is expected during pregnancy. Uterine leiomyomas will also cause the uterus to enlarge. Skin hyperpigmentation occurs on the face, abdomen, axilla, areola, and nipples during pregnancy and is caused by the increase in estrogen, progesterone, and melanocyte-stimulating hormone.

It should be noted that conditions other than pregnancy can cause symptoms similar to those of pregnancy. Obesity and gynecologic conditions can cause hyperpigmentation. Uterine fibroids could be mistaken for palpation of a fetus. A positive or negative pregnancy test may be inaccurate or caused by a medical condition (such as ovarian cancer or pituitary disease).

Positive Signs of Pregnancy

The positive signs of pregnancy directly confirm a person is pregnant and include auscultation of the fetal heart rate, palpable fetal movement by the examiner, and visualization of the embryo or fetus via ultrasound. Fetal heart tones (FHT) can be heard by Doppler as early as 10 weeks of gestation. Fetal movement can be felt when palpating the uterus. An ultrasound can confirm cardiac activity and the size and location of the embryo or fetus.


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