Short interpregnancy intervals and the risk of adverse birth outcomes among five racial/ethnic groups in the United States.
The authors studied the effects and population-level impact of short (< or = 12 months) interpregnancy intervals on the risks for low (<2.5 kg) birth weight and preterm (<37 weeks) delivery of liveborn singleton infants to US African American, Mexican, Native American, non-Hispanic white, and Puerto Rican mothers (n = 4,841,418) from 1989 to 1991. Statistical analyses were done by using the Mantel-Haenszel correlation statistic chi-square test and logistic regression. The proportion of livebirths associated with < or =12-month interpregnancy intervals was the lowest among non-Hispanic whites (18.5%, 95% confidence interval 18.5-18.5) and the highest among Native Americans (29.7%, 95% confidence interval 29.2-30.2). As compared with mothers with >12-month intervals, mothers with <6-month intervals had an approximately 50% to 80% increased risk of very low (<1.5 kg) birth weight delivery and a 30% to 90% increased risk of very preterm (<32 weeks) delivery. Logistic regression analyses showed that the adverse effects of short intervals were reduced by about 10% but remained for the most part significant after controlling for potential confounding by maternal age, education, parity, marital status, prenatal care, smoking, and previous preterm delivery.
Khoshnood
B
B
Department of Pediatrics, University of Chicago Children's Hospital, IL 60637, USA.
Lee
K S
KS
Wall
S
S
Hsieh
H L
HL
Mittendorf
R
R
D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D001721:Birth Intervals; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D007198:Indians, North American / Q000706:statistics & numerical data; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000208:ethnology*; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data