Short interpregnancy intervals and risks for birth defects: support for the nutritional depletion hypothesis

Area of Science:

• Reproductive Health
• Perinatal Epidemiology
• Nutritional Science

Background:

• Short interpregnancy intervals are linked to increased risks of adverse perinatal outcomes, including certain birth defects.
• Nutritional depletion, particularly of folic acid (FA), is a hypothesized contributing factor.

Purpose of the Study:

• To evaluate the association between short interpregnancy intervals and select malformations.
• To examine the combined effect of interpregnancy interval and folic acid (FA) intake on malformation occurrence.

Main Methods:

• Utilized data from the National Birth Defects Prevention Study (1997-2011).
• Analyzed case-control data from multiparous women, comparing malformed infants (cases) with non-malformed infants (controls).
• Categorized interpregnancy intervals (<6, 6-11, 12-17, 18-23 months) and periconceptional FA intake, controlling for covariates.

Main Results:

• Short interpregnancy intervals (<6 months) were associated with increased odds ratios (>1.2) for several noncardiac and cardiac malformations compared to longer intervals (18-23 months).
• The risk of malformations was notably higher with short interpregnancy intervals and low folic acid (FA) intake (<400 µg/d DFE, no supplement use).
• Folic acid (FA) supplementation appeared to mitigate the increased risk associated with short interpregnancy intervals for most defects.

Conclusions:

• Short interpregnancy intervals show a trend towards increased risks for specific birth defects, particularly when folic acid (FA) supplement use is absent.
• This study provides preliminary evidence linking shorter interpregnancy intervals and potential nutritional deficiencies to birth defect etiologies.
• Further research with larger sample sizes is necessary to elucidate the precise role of FA and other nutrients in defect-specific outcomes.