Hypertensive disease in women of childbearing age is usually essential hypertension, but secondary causes should be considered: coarctation of the aorta, pheochromocytoma, hyperaldosteronism, and renovascular and Renal hypertension.
Preeclampsia is superimposed on 20% of pregnancies in hypertensive women and appears earlier, is more severe, and is more often associated with intrauterine growth retardation. It may be difficult to determine whether or not hypertension in a pregnant woman precedes or derives from the pregnancy if she is not examined until after the 20th week.
Serum uric acid can help differentiate, since it is elevated with preeclampsia and generally normal in chronic hypertension unless the patient is receiving diuretics. If hypertension persists for 6-8 weeks postpartum, essential hypertension is likely.
Pregnant women with chronic hypertension require medication only if the diastolic pressure is sustained at or above 100 mm Hg. For initiation of treatment, methyldopa has the longest record of safety in a dosage of 250 mg orally twice daily, increasing in divided doses as needed to as much as 3 g daily. The goal is to keep the diastolic pressure between 80 mm Hg and 100 mm Hg.
If a hypertensive woman is being managed successfully by medical treatment when she registers for antenatal care, one may generally continue the antihypertensive medication. Diuretics may be continued in pregnancy. ACE inhibitors should be replaced with a drug of another class because of reports of fetal and neonatal renal failure with these compounds.
Use of antihypertensive medications in preeclampsia remains controversial. This should be attempted only with significant fetal prematurity, absence of fetal compromise, and close supervision of the patient.
Therapeutic abortion may be indicated in cases of severe hypertension during pregnancy. If pregnancy is allowed to continue, the risk to the fetus must be assessed periodically in anticipation of early delivery. An early second-trimester ultrasound examination will confirm the duration of pregnancy, and follow-up examinations after 28 weeks will evaluate intrauterine growth retardation.
Barrilleaux PS et al: Hypertension therapy during pregnancy. Clin Obstet Gynecol 2002;45:22.
Revision date: July 3, 2011
Last revised: by Dave R. Roger, M.D.