Maternal Pre-pregnancy Body Mass Index Categories and Infant Birth Outcomes: A Population-Based Study of 9 Million Mother-Infant Pairs

Xin'nan Zong; Huan Wang; Liu Yang; Yajun Guo; Min Zhao; Costan G Magnussen; Bo Xi

doi:10.3389/fnut.2022.789833

Maternal Pre-pregnancy Body Mass Index Categories and Infant Birth Outcomes: A Population-Based Study of 9 Million Mother-Infant Pairs

Front Nutr. 2022 Feb 17:9:789833. doi: 10.3389/fnut.2022.789833. eCollection 2022.

Authors

Xin'nan Zong^{1

2}, Huan Wang¹, Liu Yang¹, Yajun Guo³, Min Zhao⁴, Costan G Magnussen^{5

6

7}, Bo Xi¹

Affiliations

¹ Department of Epidemiology, School of Public Health, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
² Department of Growth and Development, Capital Institute of Pediatrics, Beijing, China.
³ Department of Epidemiology, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA, United States.
⁴ Department of Toxicology and Nutrition, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, China.
⁵ Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia.
⁶ Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland.
⁷ Centre for Population Health Research, University of Turku, Turku University Hospital, Turku, Finland.

Abstract

Background and aims: Infant adverse birth outcomes have been suggested to contribute to neonatal morbidity and mortality and may cause long-term health consequences. Although evidence suggests maternal prepregnancy body mass index (BMI) categories associate with some birth outcomes, there is no consensus on these associations. We aimed to examine the associations of maternal prepregnancy BMI categories with a wide range of adverse birth outcomes.

Methods: Data were from a population-based retrospective cohort study of 9,282,486 eligible mother-infant pairs in the U.S. between 2016 and 2018. Maternal prepregnancy BMI was classified as: underweight (<18.5 kg/m²); normal weight (18.5-24.9 kg/m²); overweight (25.0-29.9 kg/m²); obesity grade 1 (30-34.9 kg/m²); obesity grade 2 (35.0-39.9 kg/m²); and obesity grade 3 (≥40 kg/m²). A total of six birth outcomes of the newborn included preterm birth, low birthweight, macrosomia, small for gestational age (SGA), large for gestational age (LGA), and low Apgar score (5-min score <7).

Results: Maternal prepregnancy overweight and obesity increased the likelihood of infant preterm birth, with odds ratios (ORs) (95% CIs) of 1.04 (1.04-1.05) for overweight, 1.18 (1.17-1.19) for obesity grade 1, 1.31 (1.29-1.32) for obesity grade 2, and 1.47 (1.45-1.48) for obesity grade 3, and also for prepregnancy underweight (OR = 1.32, 95% CI = 1.30-1.34) after adjusting for all potential covariates. Prepregnancy overweight and obesity were associated with higher odds of macrosomia, with ORs (95% CIs) of 1.53 (1.52-1.54) for overweight, 1.92 (1.90-1.93) for obesity grade 1, 2.33 (2.31-2.35) for obesity grade 2, and 2.87 (2.84-2.90) for obesity grade 3. Prepregnancy overweight and obesity was associated with higher odds of LGA, with ORs (95% CIs) of 1.58 (1.57-1.59) for overweight, 2.05 (2.03-2.06) for obesity grade 1, 2.54 (2.52-2.56) for obesity grade 2, and 3.17 (3.14-3.21) for obesity grade 3. Prepregnancy overweight and obesity were also associated with higher odds of low Apgar score, with ORs (95% CIs) of 1.12 (1.11-1.14) for overweight, 1.21 (1.19-1.23) for obesity grade 1, 1.34 (1.31-1.36) for obesity grade 2, and 1.55 (1.51-1.58) for obesity grade 3.

Conclusion: Our findings suggest maintaining or obtaining a healthy body weight for prepregnancy women could substantially reduce the likelihood of important infant adverse birth outcomes.

Keywords: body mass index; large for gestational age; low birthweight; macrosomia; obesity; pre-pregnancy; preterm birth; small for gestational age.