Prenatal Visits and Screening
In normal pregnancies, the symphysis-fundal height measurement in centimeters roughly equals the gestational age in weeks. At 20 weeks gestation, the fundus of the uterus can be palpated at the level of the umbilicus. A symphysis-fundal height measurement that differs from the gestational age in weeks by 3 or more centimeters is abnormal and requires ultrasound to estimate the fetal weight and measure amniotic fluid volume. Common causes of small symphysis-fundal height measurement include oligohydramnios (i.e., low amniotic fluid volume) and fetal growth restriction.
Fatigue, back pain, and anemia occur during normal pregnancy. Many maternal physiologic adaptations to pregnancy can be mistaken for evidence of disease. During pregnancy, there is an increase in cardiac output, which can manifest as a systolic ejection murmur that is typically low-grade. Elevated progesterone levels can increase the respiratory rate and drive, which results in a gradual onset of dyspnea (difficulty breathing).
All pregnant women are screened for anemia during pregnancy. Physiologic anemia is pregnancy's most common hematologic abnormality due to blood volume expansion of approximately 50% while the red blood cell mass only expands by 25%. Because of this, iron requirements increase during pregnancy. Failure to maintain adequate iron levels may result in adverse maternal and fetal effects secondary to iron deficiency.
Neural tube defects (NTD) result from the failure of the neuropores to close during development. Risk factors include a family history of NTD, poorly controlled diabetes, use of seizure medications, and low folate stores. Preconception folate supplementation (0.4 mg/day) significantly reduces the incidence of NTDs and is recommended for all women of reproductive age.
Gestational diabetes mellitus (GDM) is a glucose intolerance that develops during pregnancy. Associated fetal complications include fetal macrosomia (larger fetal size), hypertensive disorders of pregnancy, perinatal mortality, and polyhydramnios (high amount of amniotic fluid). During pregnancy, hormones like human placental lactogen and human placental growth hormone cause increased insulin resistance to ensure an adequate supply of glucose in the maternal blood for the growing fetus. However, this insulin resistance if too high can lead to gestational diabetes. Women have universal screening for gestational diabetes between 24 and 28 weeks gestation (just after the concentrations of these hormones peak). Screening involves a 50 g oral glucose load, followed by serum glucose measurement at 1 hour. A screen is considered positive if serum glucose is greater than 135 mg/dL at 1 hour, in which case a diagnostic 3-hour oral glucose tolerance test (GTT) is administered. Women are told to fast for at least 8 hours. A fasting blood glucose is first drawn. Then, a 100 g oral glucose load is administered, followed by serum glucose measurements at 1, 2, and 3 hours. If two readings are above the normal range, the test is positive for gestational diabetes. There is also a one-step approach that involves a fasting 75-gm 2-hour oral GTT. A fasting plasma glucose value of more than 92 mg/dL, a 1-hour value over 180 mg/dL, or a 2-hour value of more than 153 mg/dL is diagnostic of GDM. Treatment of GDM includes exercise, dietary modification, and blood sugar monitoring. Insulin can be added if these interventions do not adequately control blood glucose levels.
Additional Prenatal Monitoring
Risk factors for risk of maternal mortality include advanced maternal age, African American or Hispanic race, multifetal gestation, and obesity.
Non-stress tests measure the fetal heart rate in response to fetal movement over time. A reactive test shows two or more accelerations within 20 minutes, each lasting 15 seconds and peaking at least 15 bpm above the baseline. A nonreactive test does not show at least two qualifying accelerations within 20 minutes.
A biophysical profile measures fetal heart rate reactivity, fetal tone, fetal movement, breathing, and amniotic fluid volume with the use of ultrasound. A normal score is 8-10 with normal amniotic fluid volume. Scores lower than 6 are associated with increased perinatal morbidity and mortality.
Complications of Pregnancy
Hyperemesis gravidarum is a severe form of physiologic nausea and vomiting during pregnancy (i.e., morning sickness). It is differentiated by intractable vomiting with dehydration, weight loss, and changes in electrolyte balance.
During pregnancy, increased estrogen and progesterone lead to cholestasis and an increased risk of gallstone formation. Gallstone-associated diseases such as calculous cholecystitis are always considered when a pregnant patient presents with pain in the right side of the abdomen.
Increased progesterone in pregnancy causes smooth muscle relaxation, decreased esophageal sphincter tone and gastric motility, and increased risk for gastroesophageal reflux.
Melasma during pregnancy presents with irregularly shaped, hyperpigmented (darker than skin tone) macules (spots or patches) arranged symmetrically on the face. Most cases resolve after pregnancy. These are treated with sun avoidance and the use of broad-spectrum sunscreen.
Preeclampsia is characterized by new onset hypertension and proteinuria (protein in the urine) and/or evidence of end-organ damage (e.g., poor kidney or live function) at > 20 weeks gestation. Preeclampsia with severe features involves the presence of blood pressure over 160/100 mmHg, platelets less than 100,000/mm3, transaminase levels at twice the normal levels, serum creatinine more than 1.2 mg/dL, or central nervous system dysfunction (e.g., visual changes, severe headaches). HELLP syndrome is a severe form of preeclampsia and is diagnosed with hemolysis (destruction of red blood cells), elevated liver enzymes, and low platelets (less than 100,000/mm3). It can present with abdominal pain, nausea, vomiting, headache, and lactate dehydrogenase over 600 U/L or more. HELLP is a rapidly progressive condition associated with a risk of bleeding, pulmonary edema (fluid in the lungs), placental abruption, hepatic rupture, and even death. Preeclampsia and HELLP place individuals at risk for seizures as well as other maternal and fetal complications. The initial management of HELLP includes stabilization with the use of magnesium sulfate for seizure prophylaxis. Once stabilization is complete, prompt delivery is indicated.
Perinatal Infections
Neonatal group B streptococcus (GBS) infection results from vertical transmission from GBS-colonized mothers and can result in neonatal sepsis, pneumonia, meningitis, or death. To prevent neonatal GBS, pregnant women undergo rectovaginal GBS culture between 36 and 38 weeks gestation. Women whose culture is positive for GBS receive intrapartum intravenous (IV) antibiotics (typically penicillin). It’s common; I tested positive for GBS in my third trimester and knew to expect IV penicillin when I came into the hospital to deliver.
Influenza during pregnancy is more likely to be complicated by hospitalization, pneumonia, intensive care unit admission, and mortality. Pregnant women are recommended to receive the inactivated influenza vaccine as soon as it is available during the flu season. Influenza vaccination decreases maternal influenza-related morbidity and mortality and provides passive neonatal immunity.
Asymptomatic bacteriuria is the presence of over 100,000 colony-forming units/mL of a single type of bacteria in a properly collected, clean-catch voided urine sample from a patient without symptoms of a urinary tract infection. Pregnant patients with asymptomatic bacteriuria are susceptible to the development of acute cystitis or pyelonephritis, and potential neonatal complications include preterm delivery, low birth weight, and perinatal mortality. In most nonpregnant patients, it is of no clinical consequence and requires no treatment; however, it is treated in women who are pregnant. Therefore, pregnant women are screened for asymptomatic bacteriuria during the first prenatal visit and treated with antibiotics as indicated. Fever, chills, nausea, vomiting, and/or flank pain are the most common presenting features of acute pyelonephritis. With additional danger signs as determined by evaluating physicians, people with pyelonephritis may need to be hospitalized.
Labor
The first stage of labor is divided into the latent phase (phase 1) and the active phase (phase 2). The active phase involves the cervix dilating from 6 cm to 10 cm (complete dilation). Phase 3 is the transition into stage 2 and delivery of the neonate. Appropriate progression is more than 1 cm of dilation every 2 hours with reassuring maternal and fetal signs. Protraction is cervical dilation of less than 1 cm every 2 hours and inadequate contractions. This is managed with labor augmentation (oxytocin). Arrest is no cervical change for over 4 hours with adequate contraction or no cervical change for over 6 hours with inadequate contractions. Arrest is managed with cesarean delivery.
Postpartum
Postpartum blues (baby blues) is a common condition that involves tearfulness, anxiety, irritability, mild depressive symptoms, insomnia, mood swings, and difficulty concentrating. It typically develops 2-3 days after delivery and lasts approximately 2 weeks. Because postpartum blues is self-limited, aside from social support and reassurance, no treatment is necessary.
Postpartum depression occurs in 10% of postpartum women and has the same criteria as a major depressive episode. Screening for postpartum depression is performed at all postpartum visits to allow for early diagnosis and intervention. Postpartum depression presents with impaired maternal-infant bonding and diminished interaction with the infant (e.g., less likely to breastfeed or play with the infant). Management is antidepressants and psychotherapy.
Postpartum psychosis is a psychiatric emergency that begins within days to weeks after childbirth with delusions, hallucinations, violent thoughts with the risk of suicide and infanticide, and delusions (i.e., feeling that the baby is connected to God or the devil in some way). It occurs in 1% of postpartum women and is managed with hospital admission, atypical antipsychotics, and mood stabilizers.