Chronic Hypertension: Does It Mean I'll Get Preeclampsia?

I am 30 years old and 13 weeks pregnant. I did not have high blood pressure prior to pregnancy, but I was recently diagnosed with chronic hypertension; the readings were 150/90 and 160/100 over a two-week period. My caregiver prescribed 250 mg of Aldomet three times a day. What are my chances of developing superimposed preeclampsia, and what's my prognosis for having a healthy baby?


Peg Plumbo CNM

Peg Plumbo has been a certified nurse-midwife (CNM) since 1976. She has assisted at over 1,000 births and currently teaches in the... Read more

I understand your concern. I will try to explain some things about chronic/essential hypertension in pregnancy. A diagnosis of chronic hypertension is made by documenting a history of high blood pressure before the pregnancy or (as in your case) with a persistent elevation (of at least 140/90) on two occasions, more than 24 hours apart, before the 20th week of gestation.

Women with chronic hypertension tend to show greater decreases in their blood pressure during pregnancy than do women with normal blood pressure readings. So you may see your blood pressure coming down in the middle of pregnancy, due to the increased relaxation of the vessel walls.

Hypertension is considered to be mild if the systolic blood pressure (the top number) is less than 160 and the diastolic (bottom number) is less than 110. In "Obstetrics: Normal and Problem Pregnancies", Gabbe states that the benefits of treating mild hypertension have not been proven. But for those with more severe forms, diastolic readings of 110 or higher, the benefits are easier to see.

When pre-eclampsia is superimposed, the systolic blood pressure goes up at least 30 mm and the diastolic goes up about 15 mm. Accompanying symptoms of swelling and protein in the urine occur, as well as an elevation of uric acid levels in the blood. In studies, the incidence of superimposed pre-eclampsia seems to be anywhere from five to 52 percent, depending upon the severity of the hypertension at the onset of pregnancy. The reported incidence for patients with mild hypertension such as yours was as low as 4.7 percent.

The outlook for a healthy pregnancy and baby does depend upon your blood pressures and whether or not you get pre-eclampsia. If your only complication is hypertension, the outcome for both you and your baby are similar to those who have no hypertension. "In general, mortality and morbidity are not increased in patients with uncomplicated mild chronic hypertension, whereas they are markedly increased in patients with severe disease, in those with renal disease and in those complicated by superimposed pre-eclampsia" (Gabbe, 1996).

Aldomet is the only antihypertensive drug for which the long-term safety for the mother and the fetus has been adequately assessed. It is the drug most commonly used to treat hypertension during pregnancy and is the standard.

Exercise, especially walking, is probably okay but your own provider should counsel you on this. Several periods of rest each day, lying on your left side for 45 minutes, would also be a great idea. This has been shown to increase birth weight in babies at risk for intrauterine growth restriction. You may also want to ask your doctor about taking a baby aspirin each day.

You should be seen extra frequently, every two to three weeks, in the first two trimesters. Home measurement of blood pressure could be added to supplement readings in the office.

I wish you the best with this pregnancy. It sounds like you're getting great care.

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