Figure 3 Interaction between gestational hypertension and history of preterm birth. (A) Model 1: univariate analysis. (B) Model 2: adjusted for age, race, and educational attainment of mother and father. (C) Model 3: adjusted for age, race, and educational attainment regarding father and mother, pre-pregnancy body mass index, weight gain during pregnancy, cigarette smoking before and during pregnancy, method of delivery, number of fetuses, payment source for delivery, previous cesarean, pre-pregnancy diabetes, gestational diabetes, infection, eclampsia, and sex of infant (R version 4.20, R Foundation for Statistical Computing).