Health Science Reports (Aug 2024)

Interpregnancy interval and adverse perinatal outcomes: A within‐individual comparative method

  • Maria Sevoyan,
  • Marco Geraci,
  • Edward A. Frongillo,
  • Jihong Liu,
  • Nansi S. Boghossian

DOI
https://doi.org/10.1002/hsr2.2313
Journal volume & issue
Vol. 7, no. 8
pp. n/a – n/a

Abstract

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Abstract Background and Aim Previously observed associations between interpregnancy interval (IPI) and perinatal outcomes using a between‐individual method may be confounded by unmeasured maternal factors. This study aims to examine the association between IPI and adverse perinatal outcomes using within‐individual comparative analyses. Methods We studied 10,647 individuals from the National Institute of Child Health and Human Development Consecutive Pregnancies Study in Utah with ≥3 liveborn singleton pregnancies. We matched two IPIs per individual and used conditional logistic regression to examine the association between IPI and adverse perinatal outcomes, including preterm birth (PTB, <37 weeks’ gestation), small‐for‐gestational‐age (SGA, <10th percentile of sex‐specific birthweight for gestational age), low birthweight (LBW, <2,500 g), and neonatal intensive care unit (NICU) admission. Point and 95% confidence interval (CI) estimates were adjusted for factors that vary across pregnancies within individuals. Results CIs did not unequivocally support either an increase or a decrease in the odds of PTB (adjusted odds ratio [aOR]: 1.31, 95% CI: 0.87, 1.96), SGA (aOR: 0.81, 95% CI: 0.51, 1.28), LBW (aOR: 1.59, 95% CI: 0.90, 2.80), or NICU admission (aOR: 0.96, 95% CI: 0.66, 1.40) for an IPI <6 months compared to 18–23‐months IPI (reference), and neither did the CIs for the aOR of IPIs of 6–11 and 12–18 months compared to the reference. In contrast, an IPI ≥24 months was associated with increased odds of LBW (aOR: 1.66, 95% CI: 1.03, 2.66 for 24–29 months; aOR: 2.27, 95% CI: 1.21, 4.29 for 30–35 months; and aOR: 2.09, 95% CI: 1.17, 3.72 for ≥36 months). Conclusions Using a within‐individual comparative method, we did not find evidence that a short IPI compared to the recommended IPI of 18–23 months was associated with increased odds of PTB, SGA, LBW, and NICU admission. IPI ≥ 24 months was associated with increased odds of delivering an LBW infant.

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