A Rising Tide: Chronic Hypertensive Women Who Get Pregnant

It should come as no surprise. The combination of the obesity epidemic and delayed childbearing in the US has fostered a novel mini-epidemic. Chronically hypertensive women are becoming pregnant in greater numbers. The trend is not just a perinatal and obstetric problem. Because half of pregnancies are unplanned and because some antihypertensive agents are contraindicated in pregnancy, primary care providers have to be comfortable with all contingencies in this specific population. Women in this cohort have an increased incidence of preeclampsia (it may be as high as 1 in 4), abruption, fetal growth retardation (a 50% risk), pre-term births (5 times the usual risk), and C-sections. Preeclampsia also develops in a higher proportion of these women before 34 weeks’ gestation.

How should primary care physicians change their practice in response? A recently published article by Seely and Ecker¹ offers guidance.

First, care must begin before pregnancy. Since we are specifically addressing women who are hypertensive before pregnancy here and who are prone to an unplanned pregnancy, they should consistently achieve JNC-7 targets. But they should also receive certain evaluations that are not typically recommended. These include a urine quantitation for protein. A baseline will help facilitate a diagnosis of preeclampsia (with increasing protein excretion) at a later date. If preeclampsia is suspected during pregnancy, a rising uric acid level may be helpful as well diagnostically.

The treatment of hypertension during pregnancy is a bit more complicated. Twenty-eight randomized trials have demonstrated that treatment during pregnancy reduces the risk of severe hypertension, but it does not reduce the risk of preeclampsia, abruption, growth restriction, or negative neonatal outcomes.

When treating hypertension in a pregnant woman, Seely and Ecker recommended the following agents:

• Methyldopa
• Labetalol
• Metoprolol (not atenolol)
• Long-acting nifedipine
• Hydralazine
• Hydrochlorothiazide

Avoid angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), which can cause a host of complications-including fetal demise!

Confusion arises as to what goal blood pressure reductions should be during pregnancy. It is known that a greater magnitude of blood pressure reduction can inhibit fetal growth. The risk for untoward drops in blood pressure is heightened in the second trimester when blood pressure typically drops in pregnant women. I agree with Seely and Ecker that a reasonable target for pregnancy blood pressure, especially in light of varying guideline levels, would be no lower than 130/80 mm Hg.

The authors favor labetalol over methyldopa. I concur. In addition, I hesitate to recommend hydralazine. This drug has been associated with more adverse effects than the others mentioned, including serious maternal hypotension.²

Breast-feeding is encouraged as long as atenolol (caution is advised because lethargy and bradycardia have been reported in babies) and ARBs are not used (inadequate evidence for safety). ACEIs may be used during breast-feeding (unlike their contraindication during pregnancy).
 
This review definitely has changed my practice. Women of childbearing age (an age higher than it used to be) with hypertension are a high-risk group that receives attention in a primary care setting. Until proved otherwise, treat these women as if they will become pregnant.           

References:
1. Seely EW, Ecker J. Chronic hypertension in pregnancy. N Engl J Med. 2011;365:439-446.
2. Magee L, Abalos E, von Dadelszen P, et al; CHIPS Study Group. Curr Hypertens Rep. 2009;11:429-436.