Association of Short and Long Interpregnancy Intervals with Adverse Birth Outcomes: Evidence from a Cross-Sectional Study in Northwest China

Abstract

Purpose

To analyze the effects of a short interpregnancy interval (IPI) (<6 months) and a long IPI (>120 months) on neonatal adverse birth outcomes including low birth weight (LBW), small for gestational age (SGA), preterm birth (PTB), and birth defects in Shaanxi Province.

Patients and Methods

A stratified multistage random sampling method was used to recruit participants who gave birth between 2010 and 2013 in Shaanxi province. A self-designed questionnaire was used to collect the information of the participants. With the confounding factors controlled, the generalized linear model (GLM) was used to investigate the association between IPI and neonatal birth outcomes. The restricted cubic spline (RCS) function was used to evaluate the dose–response relationship between IPI and birth outcomes.

Results

A total of 13,231 women were included. The prevalence of LBW, SGA, PTB, and birth defects was 3.24%, 12.96%, 2.93%, and 2.12%, respectively. GLM showed that a short IPI (<6 months) was associated with a higher risk of SGA (RR=1.25, 95% CI: 1.04–1.52) and birth defects (RR=2.55, 95% CI: 1.45–4.47), and a long IPI (≥120 months) was associated with a higher risk of LBW (RR=1.54, 95% CI: 1.01–2.34) and PTB (RR=1.73, 95% CI: 1.08–2.76) than an IPI of 18–23 months. The RCS showed that LBW, SGA, and PTB demonstrated a j-shaped relationship with IPI (P for overall association < 0.001 for these three birth outcomes), and birth defects (P for overall association <0.001) had an inversely non-linear relationship with IPI.

Conclusion

Both short and long IPIs are associated with an increased risk of adverse birth outcomes.

Keywords:

• interpregnancy interval
• low birth weight
• small for gestational age
• preterm birth
• birth defects

Data Sharing Statement

The data used and/or analyzed during the study are available from the corresponding author’s (SD or HY) on reasonable request.

Ethics Approval and Consent to Participate

This study was approved by the Medical Ethics Committee of Xi’an Jiaotong University (No. 20112008). There were no participants under 18 years of age and information about newborns was provided by their mothers. Written informed consent was obtained from all participants prior to questionnaire administration. This study was performed in accordance with the ethical standards of the Declaration of Helsinki.

Acknowledgments

The authors would like to thank all the families in the study and all the investigators. We are also grateful to the local hospitals, health administrative departments and the Ministry of Health in Shaanxi province for their support in coordinating field work and data collection. This study was supported by National Natural Science Foundation of China (No. 81230016), Shaanxi Health and Family Planning Commission (No. Sxwsjswzfcght2016-013), the Natural Science Basic Research Plan of the Shaanxi Province (No. 2020JM-077) and National Key R&D Program of China (No. 2017YFC0907200, 2017YFC0907201). These sponsors had no role in the design, data collection, and writing of this manuscript.

Disclosure

The authors report no conflicts of interest in this work.