Stillbirth is an understudied problem that imposes a tremendous burden of disease worldwide. In the United States nearly 26,000 stillbirths were reported in 2005, almost equaling the number of infant deaths that year. U.S. blacks experienced 11.13 fetal deaths at e20 weeks gestation per 1000 births, which is in stark contrast to the fetal death rate of 4.79 among U.S. whites. The reasons for the enduring disparity in stillbirth incidence rates today between white and black woman remain largely unknown. One possibility, however, may be related to maternal weight before and during pregnancy. We propose to test the hypothesis that extremes of maternal weight before and during pregnancy contribute to the black-white disparity in stillbirth.
Our specific aims are (1) To determine the independent and joint contribution of maternal prepregnancy body mass index (BMI) and weight gain during pregnancy to the risk of antepartum stillbirth. (2) To evaluate the contribution of maternal pregravid BMI and weight gain during pregnancy to the black-white disparity in antepartum stillbirth. (3) To evaluate the independent and joint association between maternal pregravid BMI and weight gain during pregnancy (pattern and total gain) and subtypes of antepartum stillbirth defined by pathophysiologic contributors or causes. To achieve these specific aims, we will conduct a case-cohort study using a population of 172,290 singleton deliveries at Magee- Womens Hospital in Pittsburgh, PA (1989 to 2009), which includes an estimated 879 antepartum stillbirths. Cases of stillbirth will be identified through state fetal death records and a hospital delivery database. Medical record review by a jury of 7 maternal-fetal medicine specialists will confirm antepartum stillbirth and define its likely cause(s) using a contemporary classification system. We will identify pathophysiologic contributors and pathways to stillbirth with a perinatal pathologist's examination of placental histology from all stillbirths. For all pregnancies in the study, we will supplement existing information in the delivery database with data on measured weights throughout gestation ascertained through medical record review. Weight gain during pregnancy will be examined two ways: pattern of gestational weight gain and total weight gain above, within, and below the revised 2009 IOM weight gain recommendations (this includes a specific examination of weight loss or no weight gain during pregnancy). Our innovative methods for defining gestational weight gain adequacy, studying pattern of weight gain, and assigning causes of stillbirth will avoid misclassification and provides clues into mechanisms linking prepregnancy weight and weight gain to fetal mortality. This novel, cost-efficient study builds upon and extends existing literature by using innovative methods to fully explore the contribution of pregravid weight and weight gain-two potentially modifiable factors-to black-white disparities in fetal death.
This work is significant because the racial disparity in fetal mortality and the epidemic of obesity in the U.S. are among the most critical problems in public health today, and our results will move these fields forward. These results may reveal new options for prevention that could reduce health care costs as well as improve survival and health of newborns.
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