Can ultrasound predict the delivery time of patients with previous cesarean section in the 37th gestational week? A prospective cross-sectional study

Background: The aim was to investigate factors that predict when patients with previous cesarean section will undergo cesarean section (CS) using ultrasonography in the 37th gestational week. Material and methods: In this prospective cross-sectional study, a total of 166 patients with previous CS who presented to the hospital for routine checks at the 370/7th gestational week were included in the study. Uterine-related, fetus-related, and patient-related factors that affect labor time were analyzed by the same physician at admission, and the patients were then divided into two groups as those having CS at early term (370/7 to 386/7 weeks of gestation) and full-term (390/7 to 406/7 weeks of gestation). Ninety-four patients underwent CS at full-term and 72 patients underwent CS at the early term in the study. Results: There was no significant difference for age (years), parity, weight gain, previous cesarean number, cervical length, myometrial thickness, estimated fetal weight, and full lower uterine segment thickness between the groups (p>.05). In the full-term group, 58% had a history of vaginal birth, whereas, in the early-term group, 42% had a history of vaginal birth (p <.05). Vaginal birth history was found to be independently associated with reaching full-term (respectively, OR: 2.876, 95% CI: [1.227–6.738]; p =.015) in all patients. Two different regression models were created to predict different CS times after the 37th week of pregnancy. Weight gain was found to be independently associated with CS time within the first seven days after admission (OR: 1.267, 95% CI: [1.003–1.599]; p =.047). Vaginal birth history and estimated fetal weight were found to be independently associated with CS time in the 8th day and further after admission (OR: 0.244, 95% CI: [0.089–0.675]; p =.007 and OR: 1.002, 95% CI: [1.000–1.003]; p =.047) Conclusion: Vaginal birth history can be useful to predict reaching full-term in patients with previous CS. Determination of such risk factors is important in terms of reducing the frequency of emergency cesarean delivery.