Conclusion
Our study indicates that an IPI of <24 months is related to a greater risk of anemia in late pregnancy. IPI may synergize with other factors to increase the risk of incomplete uterine rupture. An extremely long IPI of ≥120 months is related to higher risks of GHP and GDM due to increasing maternal age. An optimal IPI and gestational age should be considered for families planning to have a second baby.