It is a common misconception that all twin pregnancies require a cesarean delivery, but many people carrying twins can successfully deliver both babies vaginally. A planned vaginal delivery is often possible and safe, provided certain conditions are met and the medical team is prepared for any shifts. The decision involves a careful assessment of multiple factors related to the babies’ health, positions, and gestational age. For well-selected twin pregnancies, current medical evidence suggests that a planned vaginal birth is associated with similar outcomes as a planned cesarean delivery.
Essential Criteria for a Vaginal Twin Delivery
The most important factor determining the feasibility of a vaginal twin delivery is the position of the first baby, Twin A. Twin A must be in the vertex, or head-down, presentation for a trial of labor to be considered safe. If the first baby is breech or transverse, a planned cesarean delivery is recommended to prevent complications.
The gestational age at the onset of labor is another consideration, with most planned vaginal twin deliveries occurring at or after 32 weeks. Earlier deliveries present a higher risk, especially if the babies are small. Twins who share an amniotic sac (monoamniotic) are generally delivered by cesarean section due to the high risk of cord entanglement.
Fetal weight estimates are evaluated; a minimal size difference between the twins is preferred. A weight discordance, where one twin is significantly larger, may preclude a vaginal delivery, especially if the smaller baby is Twin A. The mother must not have contraindications to labor, such as a prior uterine incision. A previous vaginal delivery can increase the likelihood of a successful twin birth.
The Mechanics of Delivering Twins
The initial phase of the vaginal delivery follows the same pattern as a singleton birth, with the mother progressing through labor to deliver Twin A. Once Twin A is born, the focus shifts immediately to the well-being and positioning of Twin B. Continuous fetal monitoring is maintained throughout the entire process for both babies using two distinct monitoring devices.
After the first baby is delivered, the obstetric team assesses the position of Twin B using ultrasound and a manual examination. If Twin B is head-down and the heart rate is reassuring, labor may resume naturally or be restarted with oxytocin to stimulate contractions. The time interval between the two births is closely observed, though a longer interval is possible if the baby remains stable.
If Twin B is not in a favorable position, the physician may attempt specific maneuvers to facilitate a vaginal birth. These interventions include an external version, where the physician attempts to turn the baby by manipulating the mother’s abdomen. An internal podalic version involves reaching into the uterus to grasp the baby’s feet and guide the baby into a breech presentation for extraction. This active management requires a highly experienced obstetrician to perform safely.
Understanding Potential Complications and Conversion to C-Section
While a vaginal delivery is often planned, complications unique to twin births necessitate that the medical team be prepared for an immediate shift to a surgical delivery. The most significant risks occur after the delivery of Twin A, when the uterine environment changes dramatically. One serious concern is umbilical cord prolapse, where the cord slips down before Twin B’s head, potentially cutting off the baby’s blood and oxygen supply.
Another complication is placental abruption, the premature separation of the placenta from the uterine wall. This risk increases after the sudden drop in uterine volume following the first birth and can be life-threatening for the second twin. Twin B may also move into an unfavorable position, such as a transverse lie, making an emergency cesarean necessary.
A vaginal twin delivery is often conducted in an operating room or a delivery suite immediately adjacent to one, with an anesthesia team present. This preparedness ensures that if a complication arises, the surgical team can intervene within minutes to deliver Twin B by cesarean section. This scenario, where Twin A is born vaginally and Twin B is born by cesarean, is known as a combined delivery.