Effects of short interpregnancy intervals on small-for-gestational age andpreterm births

We examined the effects of short interpregnancy intervals on small-for-gest ational age and preterm births in a biracial population using North Carolin a birth certificate data from 1988 to 1994. We defined small-for-gestationa l age birth as being below the 10th percentile on a race-, sex, and parity specific growth curve after a gestation of 37-42 weeks. We defined preterm birth as a gestation of less than 37 weeks. We analyzed birth records from all eligible singleton births to black or white women ages 15-45 years afte r an interpregnancy interval of 0-3 months (N = 11,451) and a random sample of singleton births after an interval of 4-24 months (N = 23,118). We defi ned interpregnancy interval exposure categories as 0-3, 4-12, and 13-24 mon ths. The multivariate adjusted odds ratio for small-for-gestational age bir ths after interpregnancy intervals of 0-3 months compared with 13-24 month intervals was 1.6 (95% confidence interval = 1.4-1.8). nle odds ratio for p reterm birth after interpregnancy intervals of 0-3 montlls was 1.2 (95% con fidence interval = 1.1-1.3). Odds ratios did not: vary substantially by rac e for either outcome.