Validity of Birth Certificate-Derived Maternal Weight Data

• Type of Material: Article
• Authors: Lisa M. Bodnar, University of Pittsburgh; Barbara Abrams, University of California, Berkeley; Marnie Bertolet, University of Pittsburgh; Alison D. Gernand, University of Pittsburgh; Sara M. Parisi, University of Pittsburgh; Katherine P. Himes, University of Pittsburgh; Timothy L Lash, Emory University
• Language: English
• Date: 2014-05-01
• Publisher: Wiley: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2014 John Wiley & Sons Ltd.
• Final Published Version (URL): http://dx.doi.org/10.1111/ppe.12120
• Title of Journal or Parent Work: Paediatric and Perinatal Epidemiology
• ISSN: 0269-5022
• Volume: 28
• Issue: 3
• Start Page: 203
• End Page: 212
• Grant/Funding Information: This project was supported by NIH grant R21 HD065807; and the Thrasher Research Fund (#9181).
• Keywords: PREGNANCY; Public, Environmental & Occupational Health; birth certificate; OBESITY; VALIDATION; EXPOSURE; RELIABILITY; Obstetrics & Gynecology; Science & Technology; NORTH-CAROLINA; Pediatrics; validity; weight; GAIN; VARIABLES; RECOMMENDATIONS; Life Sciences & Biomedicine
• Research Categories: Health Sciences, Obstetrics and Gynecology; Health Sciences, Epidemiology

Abstract

Background: Studies using vital records-based maternal weight data have become more common, but the validity of these data is uncertain. Methods: We evaluated the accuracy of prepregnancy body mass index (BMI) and gestational weight gain (GWG) reported on birth certificates using medical record data in 1204 births at a teaching hospital in Pennsylvania from 2003 to 2010. Deliveries at this hospital were representative of births statewide with respect to BMI, GWG, race/ethnicity, and preterm birth. Forty-eight strata were created by simultaneous stratification on prepregnancy BMI (underweight, normal weight/overweight, obese class 1, obese classes 2 and 3), GWG (<20th, 20-80th, >80th percentile), race/ethnicity (non-Hispanic white, non-Hispanic black), and gestational age (term, preterm). Results: The agreement of birth certificate-derived prepregnancy BMI category with medical record BMI category was highest in the normal weight/overweight and obese class 2 and 3 groups. Agreement varied from 52% to 100% across racial/ethnic and gestational age strata. GWG category from the birth registry agreed with medical records for 41-83% of deliveries, and agreement tended to be the poorest for very low and very high GWG. The misclassification of GWG was driven by errors in reported prepregnancy weight rather than maternal weight at delivery, and its magnitude depended on prepregnancy BMI category and gestational age at delivery. Conclusions: Maternal weight data, particularly at the extremes, are poorly reported on birth certificates. Investigators should devote resources to well-designed validation studies, the results of which can be used to adjust for measurement errors by bias analysis.