Univariate analysis of the correlation between IPIs and pregnancy outcomes (Table 2)
Compared with the other three groups, women with an IPI of 120 months or greater had a higher rate of GHP (6.1%, p < 0.036) and GDM (34.9%, p = 0.001). There were statistically significant differences in the incidence of uterine rupture among the four groups (p = 0.041), and the proportion of uterine rupture in women with an IPI of 120 months or greater (4.9%, n = 12) was significantly lower than that among women in the other three groups. No significant difference was found across the four groups regarding to maternal outcomes, including anemia, low placenta, placenta previa, pernicious placenta, placenta accreta, placental abruption, PROM, PPH, and hysterectomy. Groups with an IPI of less than 24 months (4.1%, n = 5) and an IPI of 120 months or greater (6.1%, n = 15) were more likely to deliver before 34 weeks of gestation (p = 0.002). Babies in the group of women whose IPI was equal to or greater than 120 months had significantly lower birth weights (p= 0.017) and shorter birth lengths (p = 0.035) than those in the other three groups. No significant difference was found across the four groups regarding to perinatal outcomes, including low 1-min Apgar score, LBW and admission to the NICU.