11.3 Care in the Second Trimester of Pregnancy

Patient Interval Data

At each follow-up prenatal visit in the second trimester, the nurse obtains patient interval data similar to data in the first trimester, such as reviewing the patient’s chart, weighing the patient, taking the patient’s blood pressure, and asking the patient for a urine specimen to perform the dipstick urinalysis. If the patient’s weight gain is more or less than expected (or weight loss has occurred) at any prenatal visit, the nurse performs a 24-hour diet recall and inquires about a change in appetite. If the patient’s BP is 140/90 mm Hg or higher prior to 20 weeks of gestation, this indicates preexisting hypertension. An elevated BP at or after 20 weeks of gestation requires further investigation and is reported to the health-care provider (ACOG, 2020c). The nurse asks the patient additional questions during the interval history throughout the second and third trimesters. One question relates to patient awareness of fetal movements. Quickening most often occurs between 16 and 20 weeks of gestation and is dependent on the patient’s habitus (physical build). Patients who are multiparous (have given birth one or more times after 20 weeks of gestation) often are aware of fetal movements sooner than primiparous (pregnant for the first time) patients. Another question the nurse asks is whether the patient is feeling any Braxton Hicks contractions. These contractions are the cause of false labor. The nurse discusses the results of any laboratory tests from the previous prenatal visit with the patient at this time as well.

The interval history is obtained at each visit in the second trimester, and the nurse asks the patient if they are currently experiencing any of the following symptoms or have experienced them since the previous prenatal visit:

• vaginal discharge, bleeding, or leaking of fluid
• persistent vomiting
• epigastric or abdominal pain
• pelvic pressure or uterine cramping
• Braxton Hicks contractions
• back pain or dysuria
• dizziness or syncope
• headache
• edema in the legs, hands, or face
• visual disturbances
• decrease in fetal movements

If the patient responds yes to any of the symptoms, the nurse asks follow-up questions and determines if any additional testing needs to be ordered. These symptoms may indicate the patient is experiencing a complication of pregnancy. Table 11.9 lists the complications of pregnancy associated with each patient symptom in the second trimester of pregnancy.

Physical Exam

The physical exam during the second trimester includes assessing for edema, measuring the fundal height, and auscultating the fetal heart rate, most often by fetal Doppler. If the patient is at less than 20 weeks of gestation, the fundus of the uterus is located by palpation, and the height of the fundus is measured using the symphysis pubis and umbilicus as landmarks (Figure 11.5). At 20 weeks of gestation and throughout the remainder of the pregnancy, the fundal height is measured in centimeters from the top of the symphysis pubis to the top of the fundus of the uterus. Between 20 and 36 weeks of gestation, the measurement of the fundal height in centimeters equals the number of weeks of gestation plus or minus 2 weeks. The fetal heart rate is counted and assessed for normal rate and rhythm. If the patient responded yes to any of the symptoms at the interval history, relevant data would be obtained at this time, such as with a speculum exam for vaginal discharge or bleeding.

Figure 11.5 Fundal Height The height of the fundus corresponds to gestation at weeks 12 through 40. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Laboratory Tests

The laboratory tests routinely performed in the second trimester are the following:

• the quad marker screen (also known as the second integrated screening if the patient had the first screening earlier in the pregnancy);
• alpha fetoprotein;
• H&H or CBC;
• gestational diabetes screens (1 hr GCT, 3 hr glucose tolerance test [GTT]); and
• a blood type, Rh, and antibody screen on pregnant persons who are Rh negative.

The quad marker screen measures the maternal serum levels of four pregnancy markers (alpha fetoprotein, hCG, unconjugated estriol, and inhibin-A) and a blood sample is drawn when the patient is between 15 and 22 weeks of gestation. After the nurse informs the patient of the purpose of the quad marker or the stand-alone alpha fetoprotein (AFP) screen, the patient decides whether to have the marker screen done. The quad marker screen is offered to all patients who are pregnant, but it is strongly encouraged when patients have risk factors for delivering a baby with chromosome abnormalities, such as when the patient is older than 35 or the patient has previously delivered a fetus or newborn with a neural tube defect. The measurement of the pregnant person’s serum level of alpha fetoprotein is encouraged for the patient to determine if there is an increased risk for neural tube defects. As in the first trimester, some patients choose not to have any of the integrated or marker screenings performed. The integrated screenings, quad marker screen, and alpha fetoprotein screen are discussed in more depth in Chapter 13 Prenatal Testing.

The patient’s hemoglobin and hematocrit (H&H) or compete blood count (CBC) is done at least once a trimester. The H&H is monitored to detect anemia. A patient whose hemoglobin drops below 10.5 g/dL during the second trimester of pregnancy because of iron deficiency anemia is usually treated with iron supplements (ACOG, 2021d). The CBC includes the iron indices to help diagnose nutritional anemia, and the platelet count is monitored for thrombocytopenia. A significant drop in the platelet count from the previously drawn CBC at the first prenatal visit or a platelet count less than 150,000 per microliter of blood is associated with liver damage and hypertensive disorders of pregnancy.

All pregnant patients are screened for gestational diabetes between 24 and 28 weeks of gestation unless they have preexisting diabetes mellitus or a confirmed diagnosis of gestational diabetes with the current pregnancy. The most commonly used diabetes screen is the 1-hour glucose challenge test (GCT). The GCT does not require the patient to be NPO before undergoing the test. The patient is instructed to drink a glucose solution (Glucola) containing 50 grams of carbohydrate (dextrose derived from corn). One hour later the patient’s blood glucose level is checked. If the glucose is elevated (>130 in serum or >140 using a fingerstick or whole blood), the patient is scheduled for a 3-hour GTT (glucose tolerance test). The patient is instructed to be NPO the night before and the morning of the test. Blood is drawn right before the patient starts drinking a glucose solution containing 100 g of carbohydrate, and at 1, 2, and 3 hours after the patient finishes drinking the solution. If the patient’s serum blood glucose level is elevated in any two out of the four blood draws, the patient is diagnosed with gestational diabetes and referred to nutritional counseling. The patient is also educated on the possible effects of gestational diabetes on the pregnancy outcome. (See Chapter 12 Pregnancy at Risk.)

Pregnant patients who are Rh negative will have their blood type, Rh, and antibody screen repeated right before or at 28 weeks of gestation. If the patient’s antibody screen is negative, the patient receives antepartum Rho(D) immune globulin (RhoGAM). Antepartum RhoGAM is administered to prevent the patient from producing antibodies against Rh-positive blood or Rh sensitization during the third trimester of pregnancy.

Complete Obstetric Ultrasound

A complete obstetric ultrasound (US) in the second trimester is performed at 16 to 20 weeks of gestation to assess the fetal anatomy. The US, performed by a trained sonographer, is used to:

• determine the location of the placenta,
• measure the fetus to determine the fetal weight and confirm the EDD,
• measure the amniotic fluid,
• observe fetal movement,
• auscultate the fetal heart rate,
• evaluate fetal anatomy including external genitalia, and
• determine the length of the cervix.

The exact gestation of the second trimester US is based on the health-care provider’s preference. Some providers prefer to assess the cervical length at no later than 16 weeks. Some parts of the fetal anatomy are not as well seen at 16 weeks, and waiting until 20 weeks can significantly decrease the number of US scans that need to be scheduled again.

Education in the Second Trimester

Education in the second trimester of pregnancy focuses on fetal milestones, nutrition and weight gain of the pregnant person, and signs of complications of pregnancy. At 16 weeks of gestation, external genitalia of the fetus are more easily viewed during the US, and meconium is starting to be produced. At 23 to 24 weeks, the fetus becomes viable because the alveoli in the lungs are starting to produce surfactant. Viability at this point in the pregnancy is defined as the fetus having the capability of living outside the uterus.

The importance of a healthy diet is reinforced in the second trimester. The nurse uses the patient’s weight gain, maintenance, or loss as the screening tool for adequate nutritional intake. Any weight loss is investigated for an underlying cause, such as illness or lack of money for food. Unexpected weight gain may be due to fluid retention or a sedentary lifestyle rather than eating nonnutritious foods. The nurse can help identify nutritious foods the patient likes and can afford.

Patient education in the second trimester may discuss the same symptoms, such as vaginal bleeding, but the complications change after 20 to 24 weeks of gestation. Uterine cramping and vaginal bleeding indicate possible abortion when the patient is at less than 20 weeks’ gestation. These same symptoms indicate possible preterm labor after 20 weeks. The presence of edema before 20 weeks may indicate heart disease; after 20 weeks, edema may be an early sign of a hypertensive disorder of pregnancy. Additional signs and symptoms of complications to discuss with the patient in the second trimester of pregnancy include the following:

• fetal growth and development
• quickening
• reinforcement of health promotion activities
• physiologic changes during the second trimester of pregnancy
• psychologic changes during the second trimester of pregnancy
• common discomforts of pregnancy
• review signs of complications
• fetal movement
• Rho(D) immune globulin if Rh negative
• laboratory testing and results
• choosing a newborn health-care provider
• breast-feeding
• childbirth preparation
• birth plan