Pregnancy outcomes of the bridal (N = 62,590), premarital birth (N = 3,130), and premarital conception groups (N = 59,460) compared with post-marital pregnancy (N = 564,749).

PTB, preterm birth; VPTB, very preterm birth; LBW, low birth weight; VLBW, very low birth weight; aOR, adjusted odds ratio.1Calculated using the χ2 test.2Adjusted for birthplace, sex, paternal and maternal age, paternal and maternal employment, and paternal and maternal education level.3Post-marital pregnancy is defined as childbirth between 10 and 24 months of marriage.4Bridal pregnancy is defined as childbirth before 5 months of marriage. It is categorized according to the following subgroups : premarital conception and premarital birth.5Premarital conception is defined as pregnancy conceived before marriage and ending after marriage.6Premarital birth is defined as childbirth before marriage.