High blood pressure during pregnancy can cause a slew of problems for mom and for baby, including low birth weight and early delivery. According to new research, it can also have long-term effects on children's thinking skills -- effects that can persist into old age.
In a new study published online in the journal Neurology on Wednesday, researchers looked at the blood pressure levels of the mothers of nearly 400 men who were born between 1934 and 1944 in Finland. Their language, math and visual spatial reasoning skills were all tested at age 20 and then again at age 69.
The men whose mothers had high blood pressure during pregnancy -- defined as a systolic blood pressure of 140 mmHg or higher, or a diastolic blood pressure of 90 mmHg or higher -- scored more than 4 points lower on the thinking tests at age 69 than the men whose mothers did not have any blood pressure problems during pregnancy. They also had the biggest decline in overall cognitive ability after the age of 20.
"This study adds to the existing literature by showing that the effects persist into old age," said Katri Raikkonen of the Institute of Behavioral Sciences at the University of Helsinki, one of the study's authors.
According to the National Heart Lung and Blood Institute, high blood pressure problems occur in up to 8 percent of all pregnancies in the U.S., approximately 70 percent of which are first-time pregnancies. Women who have high blood pressure before becoming pregnant have a higher chance of developing preeclampsia -- a condition in which pregnant women develop high blood pressure and protein in their urine after the 20th week of pregnancy.
One of the main risks posed by high blood pressure during pregnancy is a decrease in the flow of blood to the placenta.
"The oxygen and nutrition being delivered to the fetus over the course of the pregnancy may not be quote, 'as good as' with an uncomplicated pregnancy. Therefore, the development of the fetus may be in some way impaired," said Dr. Peter Bernstein, maternal fetal medicine specialist and director of perinatal safety and quality at Montefiore Medical Center in New York. (Bernstein was not associated with the new study.)
But Bernstein stressed that, in this study, the differences in cognition between men born to mothers who had high blood pressure and those born to mothers whose blood pressure was normal were minimal.
"We're not talking about the difference between normal cognitive abilities and being mentally disabled," he said. Bernstein also cautioned that the data used to determine the mothers' blood pressure was collected in the 1930s and 40s, and that medicine and surveying techniques have improved greatly since then. The researchers did adjust for many factors that may have affected outcomes, such as length of gestation and a mom's age and body mass index at delivery. But they did not adjust for maternal stress or smoking.
Nonetheless, the new study serves as yet another reminder of the importance of monitoring and treating blood pressure issues during pregnancy and before.
"If you're hypertensive, getting good care and choosing when to get pregnant is important," Bernstein said. "Optimizing your health before you conceive the pregnancy is a very important step to reducing complications."
Raikkonen also stressed that babies' brains continue to develop after birth, so providing good postnatal care -- like simply being a "sensitive parent" -- can help mitigate any negative effects.