Are interpregnancy intervals between consecutive live births among black women associated with infant birth weight?

The purpose of this study was to determine whether the length of interpregnancy intervals between consecutive live births among Black women had any significant effect on mean birth weight as had previously been reported in another study.

We examined a sample (1,048 women, 66% of study participants) from a study of non-Hispanic Black women whose infants were born at a large, inner-city, public hospital in Georgia from October 1988 through August 1990. Data were evaluated for the 494 women whose current and immediately previous pregnancies ended in the birth of a live infant weighing 500 grams or more.

Linear regression and analysis of covariance models were developed.

The median interpregnancy interval was 15 months (range 1 to 207 months), with 19 (4%) of the women having intervals of less than 3 months. After adjustment for parity, gestational age (in weeks), and smoking status, the mean birth weight associated with an interpregnancy interval of three or more months was 3,106 grams, 215 grams greater than that for an interval of less than three months (P = .06).

Although longer birth spacing has been associated with certain positive social and health effects, the population attributable effect on infant birth weight may not be very significant.