Atenolol and propranolol have been associated with fetal growth restriction, metoprolol to a lesser degree.
Metoprolol is useful in women with coronary artery disease, tachyarrhythmias, and/or requiring migraine prophylaxis during pregnancy.
Nifedipine is often used as a second-line agent, with extended-release preparation preferred. Short-acting nifedipine should be used with caution during pregnancy due to the potential for acute impairment of uteroplacental flow. However, short-acting nifedipine is used for tocolysis in pre-term labor.
Intravenous hydralazine is another option for acute treatment in the setting of severe hypertension/preeclampsia.
Angiotensin-converting enzyme (ACE) inhibitors are contraindicated during pregnancy due to association with increased rates of cardiovascular and central nervous system malformations when used in the first trimester, as well as fetal anuric renal failure when used later in pregnancy.21 Due to similar mechanisms of action, angiotensin receptor blockers (ARBs) are contraindicated.
In general, antihypertensive agents are considered compatible with lactation, with most minimally excreted into breast milk. Women requiring antihypertensive agents or almost any medication during lactation seek particular reassurance from caregivers.
It is essential to emphasize the benefit of breastfeeding for both mother and newborn, which far outweighs the risk of medication exposure to the newborn—with rare exceptions. Enalapril and captopril are considered compatible with breastfeeding by the American Academy of Pediatrics.22
Q: Can we identify and possibly prevent preeclampsia?
Escalating hypertension or maternal symptoms, especially in women with increased risk factors, warrant careful examination and laboratory assessment for preeclampsia. Physical findings may include retinal vasospasm, rales on pulmonary exam, cardiac gallop, RUQ or midepigastric tenderness from hepatic capsule stretching, nondependent edema (e.g., face, hands), or clonus on deep tendon reflex evaluation. Useful laboratory values include complete blood count, serum creatinine, hepatic transaminases, uric acid, and urinalysis.
Marked anemia or hemoconcentration, thrombocytopenia, SCr ≥0.8 mg/dL, transaminases above normal, uric acid ≥5.0 mg/dL, urine protein 1+ or greater on dipstick, are all suggestive of preeclampsia, particularly if worsened compared to prior values. Urine protein-to-creatinine ratios have not reliably correlated with 24-hour urine protein collections in preeclamptic patients, although very high or low values could be helpful.23
Women are typically admitted for fetal monitoring, 24-hour urine protein collection, and blood-pressure management during a preeclampsia evaluation.
Thus far, the only intervention shown to reduce the likelihood of preeclampsia in women at increased risk is low-dose aspirin. A recent meta-analysis noted 10% reduction of relative risk of preeclampsia and pre-term birth prior to 34 weeks in women with history of preeclampsia treated with aspirin from the second trimester onward.24 Other interventions in trials that have not displayed reduced risk include vitamin C, vitamin E, calcium, fish oil, zinc, magnesium, and antihypertensive therapy.
Back to the Case
Our patient has chronic hypertension and diabetes, so she should have a blood-pressure goal of <130/80 mmHg. She could be initiated on methyldopa or labetalol. She should have a screen for secondary hypertension via exam and serum thyrotropin, potassium, and calcium, as well as baseline “preeclampsia labs”: complete blood count, serum creatinine, transaminases, uric acid, and 24-hour urine protein assessment. Aspirin at 81 mg daily should be considered from 12 weeks gestation to delivery.
Glycemic control is critical in early gestation to avoid increased risk for congenital malformations and spontaneous abortion, and later on to minimize macrosomia. Close monitoring for maternal symptoms of preeclampsia and blood-pressure assessment is advisable. With medical comorbidities of hypertension and diabetes mellitus, the woman’s risk of preeclampsia is at least 25%. Her pregnancy dating should be confirmed by a first-trimester ultrasound.
Bottom Line
A pregnant woman with chronic hypertension should have evaluation for secondary causes of hypertension, adjustment or initiation of preferred antihypertensive agents to achieve blood pressures that minimize the risk for acute hypertensive complications and fetal growth impairment, and close monitoring for superimposed preeclampsia. TH