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Subfertility and the risk of low birth weight
M A Williams1, M B Goldman, R Mittendorf
1Harvard School of Public Health, Boston, Massachusetts.
Objective:
We evaluated the association between subfertility and low birth weight infants.
Design:
Women in this analysis participated in a cross-sectional investigation of maternal risk factors for adverse pregnancy outcomes.
Setting:
Medical and obstetric history and life style information were obtained from women who delivered at the Boston Hospital for Women, 1977 to 1980.
Patients, Participants:
Our analysis was restricted to nondiabetic married women who planned their pregnancies and subsequently delivered viable singletons (3,622). The 644 "subfertile" women (no conception during a year of unprotected intercourse) were compared with 2,978 "fertile" women (conception within 1 year).
Main Outcome Measure(S):
The relative risk of low birth weight was estimated using the cumulative incidence risk ratio.
Results:
After adjusting for confounding, the relative risk of delivering a low birth weight infant (less than 2,500 g) for subfertile women versus fertile women was 1.9 (95% confidence interval [CI], 1.3 to 2.8). The adjusted relative risk of delivering a term low birth weight (intrauterine growth retarded) infant was 2.3 (95% CI, 1.2 to 4.4).
Conclusions:
In these data, subfertility is a predictor for low birth weight. The association may result from endocrinological, immunological, cervical, or other factors that interfere with optimal fetal growth.