Tampa, FL (June 18, 2010) — Extremely obese women are at greatly increased risk for hypertension in pregnancy – a potential deadly complication — compared to their normal-weight counterparts, new research by the University of South Florida shows.

The findings by Dr. Hamisu Salihu and colleagues at USF Health were recently published online in the international obstetrics and gynecology journal BJOG.

High blood pressure problems, known as pre-eclampsia, affect approximately 6 to 8 percent of pregnancies in the United States, typically starting after the 20th week of pregnancy, according to the National Heart, Lung and Blood Institute. If unchecked, this condition can threaten the lives of both the mother and fetus.

The proportion of super-obese people – those with a body mass index (BMI) greater than 50 – has increased five-fold over the last two decades, said Dr. Salihu, professor of epidemiology at the USF College of Public Health. An example of super-obesity would be a 5-foot, 4-inch woman weighing 300 or more pounds.

While obesity before pregnancy has been identified as a risk factor for pre-eclampsia, there is little information on the risks for this growing group of “super-obese” women.

The USF researchers reviewed all birth records in Missouri from 1989 to 2005 (854,085 live births) to examine the correlation between degrees of obesity and the risk for pre-eclampsia. They found that obese women (BMI of 30 or higher) were three times more likely to develop pre-eclampsia than women normal-weight women (BMI of 25 or less).

The overall rate of pre-eclampsia was 4.5 percent. The rate was 3.3 percent for normal-weight women, ranged from about 8 to 11 percent for obese women, and was 13.4 percent for super-obese women.

Regardless of their BMI, the more weight women gained during pregnancy, the higher their risk for pre-eclampsia. The risk for pre-eclampsia in super-obese women with high weight gain was more than 13 times that of normal-weight women with moderate weight gain, and more than four times that of obese women with moderate weight gain.

Physicians should work with obese, and particularly super-obese, women to help make pregnancy less risky for them and their babies, Dr. Salihu said. “Super-obese women would benefit significantly from weight loss before becoming pregnant, and appropriate, well-controlled weight gain during pregnancy.”

Journal article online:
“Super-obesity and risk for early and late pre-eclampsia;” AK Mbah, JL Kornosky, S Kristensen, EM August, AP Alio, PJ Marty, V Belogolovkin, K Bruder, HM Salihu; BJOG; May, 19, 2010; DOI: 10.1111/j.1471-0528.2010.02593.x