|Title||Maternal prepregnancy body mass index and risk of spontaneous preterm birth.|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Shaw GM, Wise PH, Mayo J, Carmichael SL, Ley C, Lyell DJ, Shachar BZion, Melsop K, Phibbs CS, Stevenson DK, Parsonnet J, Gould JB|
|Corporate Authors||March of Dimes Prematurity Research Center at Stanford University School of Medicine|
|Journal||Paediatr Perinat Epidemiol|
|Date Published||2014 Jul|
|Keywords||Adult, African Americans, Body Mass Index, California, Cohort Studies, European Continental Ancestry Group, Female, Gestational Age, Hispanic Americans, Humans, Obesity, Obstetric Labor, Premature, Parity, Pregnancy, Pregnancy Complications, Premature Birth|
BACKGROUND: Findings from studies examining risk of preterm birth associated with elevated prepregnancy body mass index (BMI) have been inconsistent.
METHODS: Within a large population-based cohort, we explored associations between prepregnancy BMI and spontaneous preterm birth across a spectrum of BMI, gestational age, and racial/ethnic categories. We analysed data for 989,687 singleton births in California, 2007-09. Preterm birth was grouped as 20-23, 24-27, 28-31, or 32-36 weeks gestation (compared with 37-41 weeks). BMI was categorised as <18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0-34.9 (obese I); 35.0-39.9 (obese II); and ≥ 40.0 (obese III). We assessed associations between BMI and spontaneous preterm birth of varying severity among non-Hispanic White, Hispanic, and non-Hispanic Black women.
RESULTS: Analyses of mothers without hypertension and diabetes, adjusted for age, education, height, and prenatal care initiation, showed obesity categories I-III to be associated with increased risk of spontaneous preterm birth at 20-23 and 24-27 weeks among those of parity 1 in each race/ethnic group. Relative risks for obese III and preterm birth at 20-23 weeks were 6.29 [95% confidence interval (CI) 3.06, 12.9], 4.34 [95% CI 2.30, 8.16], and 4.45 [95% CI 2.53, 7.82] for non-Hispanic Whites, non-Hispanic Blacks, and Hispanics, respectively. A similar, but lower risk, pattern was observed for women of parity ≥ 2 and preterm birth at 20-23 weeks. Underweight was associated with modest risks for preterm birth at ≥ 24 weeks among women in each racial/ethnic group regardless of parity.
CONCLUSIONS: The association between women's prepregnancy BMI and risk of spontaneous preterm birth is complex and is influenced by race/ethnicity, gestational age, and parity.
|Alternate Journal||Paediatr Perinat Epidemiol|