Longitudinal study of growth and adiposity in parous compared with nulligravid adolescents.

OBJECTIVE To examine the impact of pregnancy on adolescent growth and adiposity relative to nulligravidas of similar maturation stage. DESIGN Prospective cohort study. SETTING The multicenter National Heart, Lung and Blood Growth and Health Study with annual examinations from 1987-1988 through 1996-1997. PARTICIPANTS One thousand eight hundred ninety girls (983 black and 907 white) aged 9 to 10 years at enrollment. MAIN EXPOSURE Self-reported number of pregnancies and births during adolescence and young adulthood (age, 15-19 years): 311 primiparas (17%), 84 multiparas (4%), 196 nulliparous gravidas (10%), and 1299 nulligravidas (69%). OUTCOME MEASURES Estimated race-specific changes in body weight, height, body mass index, waist circumference, hip circumference, waist to hip ratio, and percent body fat, defined as the difference between baseline and measurements 9 to 10 years later. RESULTS Thirty-one percent of black and 10% of white girls gave birth during adolescence and young adulthood. We found evidence of race by pregnancy interactions (P < .10) for changes in weight, body mass index, hip circumference, and percent body fat. Black primiparas and multiparas, respectively, had smaller decrements in waist to hip ratio (0.019 and 0.023) and greater increments in weight (3.6 and 6.0 kg), body mass index (1.3 and 2.3), waist circumference (3.5 and 5.2 cm), hip circumference (2.1 and 4.0 cm), and percent body fat (3.4% and 4.6%) than black nulligravidas after adjustment for baseline measurements, age, study center, family income, parental education, age at menarche, hours of television and video viewing, and height at visit 9 or 10 in weight models (P < .01). White primiparas had borderline greater increments in waist circumference (2.4 cm) and percent body fat (0.9%) and smaller decrements in waist to hip ratio (0.017) than white nulligravidas (P < .05). Height did not differ by pregnancy status. CONCLUSIONS Women who give birth during adolescence and young adulthood have substantially greater increments in overall and central adiposity than adolescents who do not experience pregnancy independent of other known correlates of weight gain.