Clinicostatistical studies on factors influencing spontaneous cephalic version of breech presentation

Singleton breech presentations are identified in 30% of second trimester pregnancies, but the incidence of breech presentations decreases to 3∼4% in the last trimester due to the spontaneous cephalic version. We assumed that if spontaneous cephalic version is inhibited, breech presentation will persist until the last trimester. In this study, the contributory factors affecting spontaneous cephalic version were assessed. We investigated 73 singleton breech presentations identified at 25th to 33rd gestational weeks. The relationship between spontaneous cephalic version and the following factors was analyzed ; maternal factors (maternal physique, size of pelvic cavity, angle of pelvic inclination and parity), fetal factors (presentation and fetal size) and fetal environmental factors (AFI, placental site, length and coils of the umbilical cord). Before delivery, 68 fetuses (93%) were converted to cephalic presentation until the 34th gestational weeks and 5 (7%) remained in breech presentation. Regarding the maternal factors, mean age, height, parity and size of pelvic cavity in both groups were similar, but body weight, body mass index (BMI) and the angle of pelvic inclination were larger in non - cephalic version group than those in cephalic version group. Fetal factors studied revealed that the percentage of frank breech presentation was higher in non - cephalic version group than that in cephalic version group. EFBW and BPD in non - cephalic version group were significantly larger than those in cephalic version group. Fetal environmental factors such as AFI, coils of the umbilical cord and thickness of placenta were similar in both groups, but the umbilical cord length in non - cephalic version group was shorter by 4cm on the average than that in cephalic version group. The incidence of placental site involving the uterine horn was obviously higher in non - cephalic version group than that in cephalic version group. The mean age at delivery in non - cephalic version group was significantly earlier than that in cephalic version group, although the mean birth weight was similar in both groups. The percentage of cesarean section in the former group was significantly higher than that in the latter group.<br> In conclusion, spontaneous cephalic version was less likely to be seen in pregnancies with maternal obesity, large angle of pelvic inclination, frank breech presentation, big fetus, short umbilical cord and implantation site involving the uterine horn. [Adv Obstet Gynecol,55(1):11-17,2003(H.15.2)]<br>