Obesity may raise the risk of stillbirth

By Amy Norton

NEW YORK (Reuters Health) - Obese pregnant women may have an increased risk of losing their baby relatively late in pregnancy, and black women appear particularly at risk, a large study suggests.

Researchers found that obese women were 40 percent more likely than normal-weight and overweight women to have their pregnancy end in stillbirth -- defined as fetal death in the 20th week of pregnancy or later.

African-American women were especially at risk. Compared with obese white women, their rate of stillbirth was 90 percent higher, the study authors report in the journal Obstetrics & Gynecology.

Part of the reason for the obesity-stillbirth link may rest in the fact that obese women are more prone to diabetes and high blood pressure in pregnancy, explained Dr. Hamisu Salihu, an associate professor at the University of South Florida in Tampa and the study's lead author.

Because black women have higher rates of these pregnancy complications than white women do, this may also help explain the racial gap, according to the researchers.

However, diabetes and high blood pressure are not the whole story, Salihu told Reuters Health, and other factors must be at work.

For example, he explained, obese women also have higher levels of lipids -- blood fats such as cholesterol. These fats suppress a substance called prostacyclin, which can narrow the blood vessels and promote blood clotting in vessels supplying the fetus.

Whatever the reason for the higher risk of stillbirth, the best way to reduce these odds is for obese women to shed weight before getting pregnant, according to Salihu.