Maternal Hypertension Linked to Lower IQ

Oct. 4, 2012— -- High blood pressure during pregnancy can cause low birth weight and early delivery, and a new study suggests it may have lasting effects on the baby's brain.

The Finnish study of nearly 400 men found those born to hypertensive mothers scored an average of four points lower on cognitive tests later in life.

"Hypertensive disorders in pregnancy predict lower cognitive ability and greater cognitive decline over decades in the adult offspring," the authors wrote in their study, published today in the journal Neurology.

One in 13 pregnant women has high blood pressure, according to the National Institutes of Health. And while most of them will have healthy babies, hypertension can lead to preeclampsia -- the leading cause of fetal complications.

"It's a fairly serious problem and one we often have to manage in the field of high-risk obstetrics," said Dr. David Hackney of UH Case Medical Center in Cleveland, Ohio. "If a woman develops preeclampsia, the treatment is to deliver the baby. But obviously you don't want to do that if it's too early."

Previous studies have linked preterm birth and low birth weight to low IQ in adulthood. But the new study suggests high blood pressure may be the earlier instigator.

"Our results may also offer mechanistic insight into why short length of gestation and small body size at birth are linked with lower cognitive ability, as hypertensive disorders are among the key reasons for prematurity and intrauterine growth restriction," the authors wrote, adding that the "propensity toward lower cognitive ability has its origins in the prenatal period, when the majority of the development of brain structure and function occurs."

Although hypertension during pregnancy can be managed with certain drugs, Hackney said women of child breaking age should eat healthy and stay active to lower their risk.

"It's important to remain healthy through early life and maximize health prior to becoming pregnant," he said.

The National Institutes of Health also recommends limiting salt intake, maintaining a healthy body weight and getting good prenatal medical care.