Low Gestational Weight Gain and Risk of Adverse Perinatal Outcomes in Obese and Severely Obese Women

• Type of Material: Article
• Authors: Lisa M. Bodnar, University of Pittsburgh; Sarah J. Pugh, University of Pittsburgh; Timothy Lash, Emory University; Jennifer A. Hutcheon, University of British Columbia; Katherine P. Himes, University of Pittsburgh; Sara M. Parisi, University of Pittsburgh; Barbara Abrams, University of California Berkeley
• Language: English
• Date: 2016-11-01
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2016 Wolters Kluwer Health, Inc.
• Final Published Version (URL): http://dx.doi.org/10.1097/EDE.0000000000000535
• Title of Journal or Parent Work: Epidemiology
• ISSN: 1044-3983
• Volume: 27
• Issue: 6
• Start Page: 894
• End Page: 902
• Grant/Funding Information: This project was supported by Thrasher Research Fund (#9181) and NIH grants R21 HD065807 and R01 HD072008.
• Keywords: OVERWEIGHT; FETAL-GROWTH; AGE; BIAS; Science & Technology; IMPACT; COHORT; BODY-MASS INDEX; ASSOCIATIONS; Life Sciences & Biomedicine; Public, Environmental & Occupational Health; KNOWLEDGE; PREGNANT-WOMEN
• Research Categories: Health Sciences, Obstetrics and Gynecology; Health Sciences, Epidemiology; Health Sciences, Public Health

Abstract

Background: Our objective was to estimate associations between gestational weight gain z scores and preterm birth, neonatal intensive care unit admission, large- and small-for -gestational age birth, and cesarean delivery among grades 1, 2, and 3 obese women. Methods: We included singleton infants born in Pennsylvania (2003-2011) to grade 1 (body mass index 30-34.9 kg/m 2 , n = 148,335), grade 2 (35-39.9 kg/m 2 , n = 72,032), or grade 3 (≥40 kg/m 2 , n = 47,494) obese mothers. Total pregnancy weight gain (kg) was converted to gestational age-standardized z scores. Multivariable Poisson regression models stratified by obesity grade were used to estimate associations between z scores and outcomes. A probabilistic bias analysis, informed by an internal validation study, evaluated the impact of body mass index and weight gain misclassification. Results: Risks of adverse outcomes did not substantially vary within the range of z scores equivalent to 40-week weight gains of -4.3 to 9 kg for grade 1 obese, -8.2 to 5.6 kg for grade 2 obese, and -12 to -2.3 kg for grade 3 obese women. As gestational weight gain increased beyond these z score ranges, there were slight declines in risk of small-for-gestational age birth but rapid rises in cesarean delivery and large-for-gestational age birth. Risks of preterm birth and neonatal intensive care unit admission were weakly associated with weight gain. The bias analysis supported the validity of the conventional analysis. Conclusions: Gestational weight gain below national recommendations for obese mothers (5-9 kg) may not be adversely associated with fetal growth, gestational age at delivery, or mode of delivery.