Interpregnancy interval and prevalence of selected birth defects: A multistate study

Abstract

Background Both short and long interpregnancy intervals (IPIs) have been associated with adverse birth outcomes. We undertook a multistate study to describe the prevalence of selected birth defects by IPI. Methods We obtained data from nine population‐based state birth defects registries for singleton live births in 2000–2009 among mothers with a previous live birth identified through birth certificates. IPI was calculated as the difference between prior birthdate and start of the current pregnancy (conception date). We estimated prevalence of selected defects per 10,000 live births and prevalence ratios (PRs) with 95% confidence intervals (CIs) overall and stratified by maternal age at previous birth and race/ethnicity. Primary analyses focused on short IPI < 6 months and long IPI ≥ 60 months compared to 18–23 months (referent). Sensitivity analyses limited to active‐surveillance states and those with<10% missing IPI. Results Among 5,147,962 eligible births, 6.3% had short IPI while 19.8% had long IPI. Compared to referent, prevalence with short IPI was elevated for gastroschisis (3.7, CI: 3.0–4.5 vs. 2.0, CI: 1.6–2.4) and with both short and long IPI for tetralogy of Fallot (short: 3.4, 2.8–4.2 long: 3.8, 3.4–4.3 vs. 2.7, 2.3–3.2) and cleft lip ± palate (short: 9.9, 8.8–11.2 long: 9.2, 8.5–9.8 vs. 8.4, 7.6–9.2). Stratified analyses identified additional associations, including elevated prevalence of anencephaly with short IPI in younger mothers and limb defects with long IPI in those ages 25–34 at prior birth. Sensitivity analyses showed similar results. Conclusion In this population‐based study, we observed increased prevalence of several birth defects with short and long IPI.

Scientific impact of the National Birth Defects Prevention Network multistate collaborative publications

“…Other risk factors investigated included environmental factors, such as ambient fine particulate matter with aerodynamic diameter ≤2.5 microm (PM 2.5), an exposure which was associated with cleft palate in offspring (Zhou et al, 2017). Interpregnancy interval is another exposure that has been evaluated, and associations between short interpregnancy interval and gastroschisis as well as tetralogy of Fallot and cleft lip with or without cleft palate have been reported (Liberman et al, 2022). A racial/ethnic difference was reported for anotia/microtia, with a higher prevalence in offspring of American Indians/Alaska Native women compared to non‐Hispanic White women (Canfield et al, 2014; Marengo et al, 2018).…”

“…Ten NBDPN publications (using pooled data from 4 to 24 surveillance programs) evaluated associations for potential risk factors with orofacial cleft defects (Zhou et al, 2017), gastrointestinal defects (Jones et al, 2016), NTDs (Boulet et al, 2008;Williams et al, 2002Williams et al, , 2005, and a spectrum of defects (Canfield et al, 2005(Canfield et al, , 2014Kirby et al, 2019;Liberman et al, 2022;Marengo et al, 2018). The most cited of these include four association studies that estimated the relative prevalence of NTDs before versus after fortification of enriched grain products in the United States with folic acid in 1998 (Boulet et al, 2008;Canfield et al, 2005;Williams et al, 2002Williams et al, , 2005, which is a major contribution and impact of NBDPN.…”