From the Research
The incidence of fetal transverse lie in primigravidas is approximately 0.3-0.4% of all pregnancies at term, as reported in the most recent study 1. This presentation is less common in first-time mothers compared to women who have had multiple pregnancies. Some key points to consider:
- Transverse lie is more frequently seen in certain conditions such as placenta previa, uterine abnormalities, multiple gestations, polyhydramnios (excess amniotic fluid), or when the mother has a relaxed uterus from previous pregnancies.
- For first-time mothers with normal uterine anatomy, the uterine walls are typically more toned, which helps guide the baby into a vertical position (either head-down or breech) as pregnancy progresses.
- Most babies who are in a transverse position earlier in pregnancy will spontaneously turn to a vertical position by the third trimester.
- However, if a transverse lie persists beyond 36 weeks, healthcare providers will typically recommend a planned cesarean delivery, as vaginal birth is not possible with a baby in this position due to the risk of umbilical cord prolapse and other complications. The study by 1 found that at the 36-week scan, fetal presentation was cephalic in 94.2% of pregnancies and either breech, transverse, or oblique in 5.8%, with transverse lie occurring in approximately 0.3% of cases. It's worth noting that the success rate of external cephalic version (ECV) for transverse lie is high, as reported in the study by 2, which found a 100% success rate for ECV in cases of transverse lie. Overall, the incidence of fetal transverse lie in primigravidas is relatively low, and most cases can be managed with ECV or planned cesarean delivery.