To assess the relationship between first-trimester vaginal bleeding and fetal growth patterns.
We conducted a secondary analysis of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies–Singletons, a prospective cohort study of low-risk, nonobese women with healthy lifestyles. Duration of bleeding was self-reported at enrollment (10 0/7 to 13 6/7 weeks of gestation) and categorized as 0, 1, or more than 1 day. Longitudinal measures of fetal biometrics were obtained in up to six study visits, and estimated fetal weight was computed. Growth trajectories were created for biometrics and estimated fetal weight. When global tests among groups was significant (P<.05), week-specific global and pairwise differences were tested. Birth weight and risk of a small-for-gestational-age (SGA) neonate were secondary outcomes. All analyses were adjusted for maternal age, weight, height, parity, and racial–ethnic group and neonatal sex in a sensitivity analysis.
In 2,307 eligible women, 410 (17.8%) reported first-trimester bleeding, of whom 176 bled for 1 day and 234 bled for more than 1 day. Women with more than 1 day of bleeding demonstrated decreased fetal abdominal circumference from 34 to 39 weeks of gestation compared with women without bleeding. For women with more than 1 day of bleeding, compared with women without bleeding, estimated fetal weight was 68–107 g smaller from 35 to 39 weeks of gestation. Mean birth weight at term was 88 g smaller, confirming differences in calculated fetal weight, and SGA neonates were delivered to 148 (8.5%), 9 (5.7%), and 33 (15.7%) women in the no bleeding, 1 day, and more than 1 day of bleeding groups, respectively.
More than 1 day of first-trimester vaginal bleeding was associated with smaller estimated fetal weight late in pregnancy driven by smaller abdominal circumference. The magnitude of decrease in birth weight was small, albeit comparable with observed decreases associated with maternal smoking. It remains unknown whether early pregnancy bleeding is associated with short-term or long-term morbidity and whether additional intervention would be of benefit.
More than 1 day of first-trimester vaginal bleeding is associated with smaller estimated fetal weight and abdominal circumference measurements beginning in the third trimester.
Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland; the Biostatistics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland; the Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina; Northwestern University Feinberg School of Medicine, Chicago, Illinois; Women and Infants Hospital of Rhode Island, Providence, Rhode Island; the Department of Obstetrics–Gynecology, University of California, Irvine, California; Fountain Valley Regional Hospital and Medical Center, Fountain Valley, California; and Glotech, Inc, Rockville, Maryland.
Corresponding author: Katherine L. Grantz, MD, MS, Epidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 6710B Rockledge Drive, MSC 7501, Bethesda, MD 20817; email: Katherine.email@example.com.
Supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (contract numbers: HHSN275200800013C; HHSN275200800002I; HHSN27500006; HHSN275200800003IC; HHSN275200800014C; HHSN275200800012C; HHSN275200800028C; HHSN275201000009C). Intramural investigators designed the study that was implemented by clinical site investigators.
Financial Disclosure Dr. Wing has been a consultant for Parsagen, for which she received no compensation. She has provided expert opinion to the company on a few clinical questions raised by the U.S. Food and Drug Administration (FDA) in the company's ongoing discussions with the FDA. The other authors did not report any potential conflicts of interest.
Presented as at the Society of Pediatric and Perinatal Epidemiologic Research Annual Meeting, June 19–20, 2017, Seattle, WA.
The authors thank the clinical centers involved in data collection for the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies (in alphabetical order): Christina Care Health Systems, Columbia University, Fountain Valley Hospital, California, Long Beach Memorial Medical Center, New York Hospital, Queens, Northwestern University, University of Alabama at Birmingham, University of California, Irvine, Medical University of South Carolina, Saint Peters University Hospital, Tufts University, and Women and Infants Hospital of Rhode Island. C-TASC and The Emmes Corporation were the data coordinating centers that provided data and imaging support for this multisite study.
Each author has indicated that he or she has met the journal's requirements for authorship.