Gestational hypertension, previously known as pregnancy-induced hypertension, is defined as hypertension in the absence of proteinuria in the latter half of pregnancy. Symptoms and lab abnormalities of preeclampsia will be absent. At least half of women with hypertension in the latter half of pregnancy progress to preeclampsia, so gestational hypertension should be considered a provisional diagnosis. Severe gestational hypertension, even without proteinuria or other lab abnormalities, carries increased perinatal risk.
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Q: What factors contribute to increased preeclampsia risk?
Maternal factors include: first pregnancy, first pregnancy with a new father, maternal age >35, particularly >40, personal or family history of preeclampsia, chronic hypertension, diabetes mellitus (Type 1, 2 or gestational), systemic lupus erythematosus, antiphospholipid antibody syndrome, renal disease, and obesity. Fetal factors include: multiple gestations, molar pregnancies, hydrops, and triploidy.5,12
Q: When should antihypertensive medications be used in pregnancy?
Most women are hesitant to expose their fetus to medication, and thus must be in therapeutic alliance with their obstetrician and consultants. The overriding principle of medication use in pregnancy is that a healthy fetus requires a healthy mother, and medication use is justified when there is definite benefit to the mother. Due to increased metabolism during pregnancy, medications otherwise dosed once per day often require two doses per day, and those dosed twice daily often require every-eight-hour dosing to maintain efficacy. Additionally, titration up every few days may be required.
Therapy goals include avoiding maternal and fetal complications from severely elevated blood pressure, as well as avoiding fetal growth restriction due to impaired uteroplacental flow. The ideal blood pressure for a hypertensive pregnant woman has not been established, but recommendations are based upon available data and expert opinion.2,5,10,12 Maternal risk of intracerebral hemorrhage increases with SBP ≥160 mmHg.16 Diastolic BP ≥110 mmHg has been associated with greater risk of placental abruption and intrauterine growth restriction.
Pharmacologic treatment generally is initiated or adjusted to achieve SBP <160 mm Hg and DBP <100 to <105 mmHg, although some societies advocate treatment initiation at 140/90 mmHg.2,5,12,17,18 If a woman has target organ damage or concomitant medical issues warranting tighter control (e.g., diabetes or pre-existing renal disease), 130/80 mmHg is preferable.19 Activity limitation and/or bed rest, although commonly recommended, have not been shown to reduce maternal or fetal morbidity or mortality, or prolong time to delivery.
An ongoing, randomized, prospective trial will compare maternal and fetal outcomes in women with mild chronic hypertension with deliberate blood-pressure stratification (goal DBP 85 mmHg vs. goal DBP 100 mmHg).20
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Q: What are reasonable treatment options for a woman with chronic hypertension during pregnancy?
Due to vasodilatation of pregnancy, antihypertensive agents often can be discontinued early in pregnancy with close, ongoing monitoring. The majority of women with mild chronic hypertension will have blood pressures <160/100 mmHg without medication during the first half of pregnancy.
If a woman has been using a pharmacologic agent not advisable during pregnancy, she could be switched to a preferred agent. If a woman has been using a pharmacologic agent preferred during pregnancy, she could continue this agent.
Q: What antihypertensives are favored during pregnancy?
Methyldopa and labetalol have been used extensively. Methyldopa has not been found to adversely affect cognitive development in children exposed in utero. On the maternal side, somnolence, dizziness, and dry mouth are common side effects.
Labetalol is widely used as a first- or second-line agent. It can be used intravenously or orally. Intravenous labetalol in escalating doses (10 mg, 20 mg, 40 mg, 80 mg) is the first line of acute treatment for severe hypertension/preeclampsia.