Changes in fetal presentation in the preterm period and the prediction of non-cephalic delivery.

OBJECTIVE: Since fetal presentation is an essential factor for planning mode of delivery, the estimation of fetal presentation at delivery is important in prenatal management. This study aimed to clarify the transition of fetal presentation during pregnancy and to propose practical strategy to predict final fetal presentation. METHODS: During the period of 2 years, fetal presentations were analyzed using ultrasonography during the prenatal visits at and after 22 weeks of gestation in a single facility. The relationship between the transition of fetal presentation and final presentation at delivery was analyzed. Further, a prediction model was developed to predict the final fetal presentation at birth. RESULTS: Among 1737 singleton pregnancies with full-term delivery, non-cephalic delivery occurred in 76 pregnancies (4.4%). Non-cephalic presentation in later half of the gestational period was associated with low incidence of spontaneous cephalic version. Furthermore, we found that in 46% of women with a final non-cephalic delivery, the non-cephalic presentation continued during whole of the observational period without spontaneous cephalic version. Based on the analyzed data of this cohort, we show that in a group of women with non-cephalic presentation at 35/36 weeks, the best predictability for spontaneous cephalic version depended on whether the cephalic presentation was observed at least once at and after 30 weeks of gestation. CONCLUSION: Our findings suggest that information on the changes in fetal presentation during gestation contributes to the prediction of the fetal presentation at delivery and planning mode of delivery.