Interactions between long interpregnancy interval and advanced maternal age on neonatal outcomes

Area of Science:

• Obstetrics and Gynecology
• Neonatal Health
• Reproductive Epidemiology

Background:

• The universal two-child policy in China has led to increased rates of long interpregnancy intervals (IPIs) and advanced maternal age.
• The combined impact of long IPIs and advanced maternal age on neonatal outcomes remains unclear.

Purpose of the Study:

• To investigate the association between interpregnancy intervals (IPIs) and neonatal outcomes.
• To examine the interaction between long IPIs and advanced maternal age on neonatal outcomes.

Main Methods:

• A historical cohort study included multiparas with singleton live births from October 2015 to October 2020.
• Logistic regression models assessed risks for preterm birth (PTB), low birth weight (LBW), small for gestational age, and low Apgar scores.
• Relative excess risk due to interaction (RERI) evaluated additive interactions between long IPIs and advanced maternal age.

Main Results:

• Long IPIs (≥60 months) were linked to higher risks of PTB, LBW, and low 1-min Apgar scores.
• Short IPIs (<12 months) also increased risks for PTB, LBW, and low 1-min Apgar scores.
• Negative additive interactions were observed between long IPIs and advanced maternal age for these adverse neonatal outcomes.

Conclusions:

• Both short and long interpregnancy intervals are associated with increased risks of adverse neonatal outcomes.
• Recommending appropriate IPIs is advised for women planning subsequent pregnancies.
• Enhanced antenatal care may mitigate risks associated with advanced maternal age and improve neonatal outcomes.