A planned vaginal birth is a potential option for many twin pregnancies, offering an alternative to a cesarean section. The approach to delivery depends on several specific factors related to the health of the mother and the condition of the babies.
Candidacy for a Vaginal Twin Birth
The possibility of a vaginal twin birth hinges on several assessments made during the pregnancy. The primary factor is the position of the first baby, known as Twin A. For a vaginal delivery to be considered, Twin A must be in a head-down (vertex) position. If the first twin is in any other position, such as breech or transverse, a cesarean delivery is recommended for the safety of both babies. The position of the second baby, Twin B, is less restrictive; a vaginal birth may still proceed if Twin B is vertex or even in a breech position, provided the obstetrician is experienced with breech deliveries.
Another determining factor is the type of twins, specifically their chorionicity and amnionicity, which refers to whether they share a placenta and an amniotic sac. The majority of twins are dichorionic-diamniotic (Di-Di), meaning each has its own placenta and sac, making them good candidates for a vaginal birth. Monochorionic-diamniotic (Mo-Di) twins, who share a placenta but have separate sacs, can also be delivered vaginally. Monochorionic-monoamniotic (Mo-Mo) twins, who share both a placenta and a sac, are delivered by a planned cesarean section because of the high risk of the umbilical cords becoming tangled or compressed.
Beyond fetal position and twin type, the overall health of the mother and babies is considered. A vaginal birth is an option for uncomplicated pregnancies that have reached at least 32 weeks of gestation. The mother should not have conditions like placenta previa, where the placenta blocks the cervix, and her pelvis should be large enough to accommodate the passage of both babies. The estimated weights of the twins are also taken into account, as a significant size difference might introduce complications.
The Delivery Room Experience
The setting for a planned vaginal twin birth differs from that of a singleton delivery. Many hospitals recommend that twin deliveries take place in an operating room rather than a standard labor and delivery room. This precautionary measure allows for a rapid transition to a cesarean section if it becomes necessary for the safety of either baby, without the delay of moving the mother.
The number of medical personnel present is also larger than for a singleton birth. The team is expanded to ensure dedicated care is available for both infants simultaneously. It includes an obstetrician, an anesthesiologist, and multiple nurses. A specialized neonatal team, including a pediatrician or neonatologist for each baby, will be present to provide immediate assessment and care as soon as they are born.
Continuous monitoring of both babies’ heart rates is a standard part of the process. This is accomplished using electronic fetal monitoring, which tracks each baby’s heart rate and the mother’s contractions throughout labor. Careful observation allows the medical team to promptly identify any signs of distress in either twin.
The Birth Process for Each Twin
The labor and delivery of Twin A proceeds in the same manner as a singleton birth. The mother will experience contractions that dilate the cervix, and she will push to deliver the baby once fully dilated. Once the first baby is born, the umbilical cord is clamped and cut, and the infant is passed to the neonatal team for assessment.
After the birth of Twin A, there is a pause while the obstetrician assesses Twin B. This assessment involves checking the baby’s heart rate, position, and lie through an abdominal examination or an ultrasound to determine the safest way for the second twin to be delivered.
The delivery of Twin B follows this assessment. In many cases, contractions resume, and the second baby is born shortly after the first, following a similar pushing stage. If Twin B is not in a head-down position, the obstetrician may need to intervene. An intervention might include an internal podalic version, where the doctor turns the baby to a feet-first position for delivery. In other situations, tools like forceps or a vacuum extractor may be used to assist with the delivery.
When a Cesarean Section Becomes Necessary
A cesarean section may be the planned mode of delivery from the outset. This occurs when specific health concerns for the mother or babies, or the position and type of the twins, make a vaginal birth less safe.
Even when a vaginal birth is planned, circumstances can arise during labor that require a shift to a cesarean delivery. Common reasons for this change include signs of fetal distress in either twin, such as a sustained drop in heart rate, or a labor that stops progressing.
In some instances, a combined delivery occurs, where Twin A is born vaginally, but Twin B requires a cesarean section. This can happen if the second twin shows signs of distress after the first is born, if the umbilical cord prolapses, or if the baby settles into a position that prevents a safe vaginal delivery. While not the most common outcome, it is a possibility that the medical team is prepared to handle.