Neonatal Nurse Practitioner Exam

The neonatal nurse practitioner is often the first provider to read the maternal chart. The exam rewards linking a maternal condition to its predictable newborn effect: preeclampsia to neutropenia and thrombocytopenia, lupus to complete heart block, pregestational diabetes to hypoglycemia and congenital anomalies, ACE inhibitor exposure to renal failure. Learn the mechanism behind each link and you can reason through unfamiliar scenarios.

This chapter reviews chronic and pregnancy-related maternal diseases and the newborn findings each one predicts, with the NNP's evaluation and management plan for the infant.

Chronic hypertension is present before 20 weeks; gestational hypertension appears after 20 weeks without proteinuria or end-organ signs; preeclampsia adds proteinuria or end-organ dysfunction (thrombocytopenia, renal insufficiency, elevated transaminases, pulmonary edema, cerebral or visual symptoms). HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) is a severe variant. The underlying lesion is abnormal placentation with poor spiral artery remodeling, which produces uteroplacental insufficiency.

Newborn consequences follow from the placental lesion and from the treatments used:

Prematurity, often iatrogenic delivery for maternal or fetal indications.

Small for gestational age (SGA) and asymmetric growth restriction.

Neutropenia in the first days of life, common in preterm infants of preeclamptic mothers, usually resolving within several days, with a modestly higher risk of nosocomial infection.

Thrombocytopenia, usually mild and self-limited.

Polycythemia from chronic fetal hypoxemia and increased erythropoietin.

Hypoglycemia from limited glycogen stores.

Effects of maternal magnesium sulfate and antihypertensives (see chapter 1.2).

Exam Tip: Neonatal neutropenia in an infant of a preeclamptic mother is expected and does not by itself mean sepsis. The NNP still evaluates clinically, but a low absolute neutrophil count with a well-appearing infant and a clear maternal explanation is the classic pattern.

Pregestational (type 1 or type 2) diabetes exposes the embryo to hyperglycemia during organogenesis, so it raises the risk of congenital anomalies; risk tracks with periconception hemoglobin A1c. Gestational diabetes begins after organogenesis, so it mainly causes fetal hyperinsulinism and its consequences rather than structural defects.

The Pedersen hypothesis explains the fetal effects: maternal glucose crosses the placenta, insulin does not, and the fetal pancreas responds with beta-cell hyperplasia and hyperinsulinism. Fetal insulin is an anabolic growth factor that drives macrosomia (with organomegaly of heart and liver) and delays surfactant maturation.

Infant of a Diabetic Mother: Expected Problems

Structural anomalies associated with pregestational diabetes include caudal regression syndrome (sacral agenesis, highly specific though rare), congenital heart disease (transposition, VSD, truncus, double-outlet right ventricle), neural tube defects, renal anomalies and small left colon syndrome. Renal vein thrombosis is another classic association.

Common Trap: The hypertrophic cardiomyopathy of the infant of a diabetic mother is a dynamic outflow obstruction. Inotropes such as dopamine or digoxin worsen it. Management is supportive with fluids, and a beta-blocker in select symptomatic infants with cardiology input.

Maternal cyanotic heart disease, severe pulmonary hypertension or poorly compensated heart failure reduce oxygen delivery to the placenta and cause growth restriction and preterm birth. When a parent has congenital heart disease, recurrence risk in the infant is higher than the general population risk, and higher when the mother rather than the father is affected; a fetal echocardiogram is appropriate. Maternal medications matter too: warfarin, ACE inhibitors, amiodarone (thyroid effects) and beta-blockers. Poorly controlled maternal asthma is associated with growth restriction and preterm birth; standard asthma medications, including inhaled corticosteroids, are considered acceptable in pregnancy.

Systemic lupus erythematosus and Sjogren syndrome produce anti-Ro/SSA and anti-La/SSB antibodies that cross the placenta and injure the fetal conduction system between about 16 and 26 weeks. Congenital complete heart block is the most serious result: fetal bradycardia (often 50 to 80 beats per minute) found on ultrasound, sometimes with hydrops. Heart block is permanent; the skin rash, cytopenias and transaminase elevation of neonatal lupus resolve over months as maternal antibody is cleared. Management of the newborn includes ECG, echocardiogram, and pacing for a very low ventricular rate (commonly under about 55 beats per minute), heart failure or a wide-complex escape rhythm. Mothers with a prior affected child have a higher recurrence risk, and hydroxychloroquine is used in pregnancy to reduce it.

Maternal immune thrombocytopenia (ITP): maternal antiplatelet IgG crosses the placenta and can cause neonatal thrombocytopenia. The neonatal platelet count often falls to a nadir at about 2 to 5 days of age, so the NNP checks a count at birth and follows it for several days. Intracranial hemorrhage is uncommon. Treat significant thrombocytopenia or bleeding with IVIG, adding platelet transfusion for active bleeding or very low counts.

Contrast with neonatal alloimmune thrombocytopenia (NAIT): the mother has a normal platelet count and the infant, often well-appearing, has severe thrombocytopenia with a higher risk of intracranial hemorrhage.

Red cell alloimmunization: maternal IgG against fetal red cell antigens (Rh D, Kell, c, E and others) causes hemolytic disease of the fetus and newborn. Anti-D titers at or above a laboratory critical value (commonly 1:16 to 1:32) prompt middle cerebral artery Doppler surveillance. Anti-Kell suppresses fetal erythropoiesis as well as causing hemolysis, so the fetus can be severely anemic with modest titers and a lower bilirubin load than expected. Rh immune globulin given at about 28 weeks and after delivery of an Rh-positive infant prevents Rh D sensitization.

Maternal sickle cell disease is associated with growth restriction, preeclampsia, preterm birth and, when the mother needs chronic opioids for pain crises, neonatal opioid withdrawal.

Graves disease: thyroid-stimulating immunoglobulins (TSI) cross the placenta and can cause fetal and neonatal thyrotoxicosis (tachycardia, goiter, irritability, poor weight gain, advanced bone age, heart failure). Even a mother who has had thyroid ablation can still carry TSI. If she is taking an antithyroid drug, the drug also crosses and may mask neonatal hyperthyroidism until it is cleared, so signs can appear at about 3 to 10 days of life. Antithyroid drugs can cause transient neonatal hypothyroidism and goiter. Methimazole in the first trimester is linked to aplasia cutis, choanal atresia and esophageal atresia, which is why propylthiouracil is often used in the first trimester.

Maternal hypothyroidism that is poorly treated may affect fetal neurodevelopment. Maternal Hashimoto thyroiditis with TSH receptor-blocking antibodies can cause transient congenital hypothyroidism.

Placental insufficiency results from maternal vascular disease (hypertension, diabetes with vasculopathy, lupus, smoking), placental abnormalities (infarcts, abruption, abnormal cord insertion) or high altitude. The fetus redistributes blood to the brain, heart and adrenals ("brain sparing"), producing asymmetric growth restriction with relative head sparing. Doppler studies track worsening placental resistance (see chapter 1.3).

Newborn problems of the growth-restricted infant: hypoglycemia (low glycogen and fat stores), hypothermia (little subcutaneous fat, large surface area), polycythemia, thrombocytopenia and neutropenia, hypocalcemia, perinatal depression with meconium passage, and a higher risk of necrotizing enterocolitis when absent or reversed end-diastolic umbilical flow was present.

Clinical Scenario: A 34-week infant weighing 1,550 g is born by cesarean for preeclampsia with HELLP and reversed end-diastolic umbilical artery flow. The NNP should anticipate hypoglycemia, polycythemia, thrombocytopenia and neutropenia, plan early glucose screening and a CBC, and use a cautious enteral feeding advance given the elevated NEC risk after abnormal fetal Doppler flow.

Preeclampsia predicts SGA, transient neutropenia, thrombocytopenia, polycythemia and magnesium effects.

Pregestational diabetes adds anomaly risk (caudal regression, heart, neural tube); gestational diabetes mainly causes hyperinsulinism effects.

Maternal anti-Ro/La antibodies cause permanent congenital heart block; neonatal lupus skin and blood findings resolve.

Maternal ITP lowers both maternal and neonatal platelets; NAIT gives severe thrombocytopenia with a normal maternal count.

Maternal Graves TSI can cause delayed-onset neonatal thyrotoxicosis even after maternal ablation.