Research News

Hypertension and placental diseases are most common causes of stillbirth in obese women, study finds

BMJ 2015; 351 doi: (Published 02 September 2015) Cite this as: BMJ 2015;351:h4658
  1. Susan Mayor
  1. 1London

The risk of stillbirth increases with increasing overweight, and hypertension and placental diseases are the most common causes of fetal death in this group, a study from the United States has found.

The researchers randomly sampled 1829 singleton deliveries from a cohort of 68 437 eligible births between 2003 and 2010 at Magee-Womens Hospital in Pittsburgh, Pennsylvania, USA.1 They added all remaining cases of stillbirth that occurred during the study period but that were not already in the random sample, giving a total of 658 cases.

Results showed that the rate of stillbirth was much higher among obese women than in those who were lean. There were 17.3 stillborn infants per 1000 births in women who were severely obese (body mass index ≥35), based on self reported weight before pregnancy, compared with only 7.7 per 1000 births in women who were lean (BMI <25).

The risk of stillbirth increased with prepregnancy body weight. After adjusting for confounding factors, the hazard ratio for stillbirth was 1.4 (95% confidence interval 1.1 to 1.8) in women who were overweight (BMI 25 to <30), 1.8 (1.3 to 2.4) in women who were obese (BMI 30 to < 35), and 2.0 (1.5 to 2.8) in severely obese women, compared with lean women.

Obesity and severe obesity were associated with stillbirths resulting from placental diseases, hypertension, fetal abnormalities, and umbilical cord abnormalities. By contrast, BMI was not related to stillbirths caused by placental abruption, obstetric conditions, or infection.

“We’ve known for some time that obese women are more likely to have stillbirths, but this is one of the first and most comprehensive efforts to figure out why,” said lead author Lisa Bodnar, associate professor at the University of Pittsburgh Graduate School of Public Health, Pittsburgh, USA.

“Our hope is that this work can be used to better counsel women on the importance of a healthy prepregnancy weight and monitor them for complications during pregnancy that may threaten the survival of their fetuses,” she explained. “Interventions to reduce stillbirth among obese mothers should consider targeting stillbirths due to hypertension or placental disease because these were the most common causes of fetal death among obese mothers.”

Bodnar added, “This study also could be used to guide prevention efforts at a societal level. If we can reduce prepregnancy obesity by even a small amount, through environmental or policy changes, we could significantly reduce the burden of stillbirth.”


Cite this as: BMJ 2015;351:h4658


View Abstract

Log in

Log in through your institution


* For online subscription