Baseline characteristics
Baseline characteristics, including demographics, pregnancy and delivery characteristics of all study participants are presented in table 1. The mean maternal age at delivery was 31.5 ± 5.2 years. Approximately four of five study participants were nulliparous (79.2%). In total, 243 (48.6%) study participants had a normal BMI, and 221 (44.2%) were overweight (29.8%) or obese (14.4%). Half of the study participants (50.8%) reported an educational level >12 years of schooling, and 15 (3%) reported smoking in early pregnancy. Five (1%) study participants had diabetes mellitus prior to pregnancy, and 66 (13%) reported pre-pregnancy recurrent urinary tract infection. In total, 28 (5.6%) study participants developed gestational diabetes and 49 (9.8%) were diagnosed with pregnancy-induced hypertensive disorder.
In total, 72 (14.4%) of deliveries occurred at early term, 247 (49.4%) at full term, 136 (27.2%) at late term, and 45 (9%) at post term gestational age. For 310 (62%) study participants, the delivery onset was spontaneous, 186 (37.2%) were medically induced and 4 (0.8%) had a cesarean delivery before labor onset. The delivery mode was non-instrumental vaginal for 136 (27.2%), instrumental vaginal for 55 (11%) and cesarean for approximately two thirds (61.8%).