Blood pressure in pregnancy: how low can you go?(Obstetrics)

ASHEVILLE, N.C. -- Aiming for "normal" blood pressure in a pregnant patient with chronic hypertension may set the fetus up for problems by worsening preexisting placental insufficiency. Dr. Christy Isler said at the annual Southern Obstetric and Gynecologic Seminar.

"Our internal medicine colleagues would like to see everyone's blood pressure at 120/80, but they are looking at preventing long-term consequences," said Dr. Isler of East Carolina University, Greenville, N.C.

"As an obstetrician, I'm just looking at getting someone safely through 9 months of pregnancy. And if I lower the blood pressure too much, I interfere with placental function. So I just want it at the tip of normal, if even that low."

While uncomplicated mild hypertension has never been proven to have negative effects on pregnancy, more severe hypertension, or preeclampsia superimposed on chronic hypertension, are much more problematic, she said.

The obstetrical risks include premature birth, intrauterine growth restriction, fetal demise, and placental abruption. "You can see that all of these outcomes are related to placental-flow problems," she said.

Preconceptional counseling is especially important for patients with chronic hypertension. "You really have to look for end organ damage in these women. Left ventricular hypertrophy is particularly complicating in pregnancy. If you see this on a screening EKG, you should really think about an echocardiogram. The increased blood volume of pregnancy along with the decreased colloid oncotic pressure is going to make a woman particularly vulnerable to heart failure if she also has LVH."

As important as lowering blood pressure is during pregnancy, the obstetrician must protect the fetus as well as the woman. Medication regimens may need to be adjusted to avoid fetal complications, and this is best done shortly after a woman conceives.