How your twins' positions in utero affect labor and delivery
There are six possible fetal presentations for twins, and each one can impact whether you'll give birth vaginally or via C-section.
As your due date approaches, you might be wondering how your twins are currently positioned in the womb, also known as the fetal presentation, and what that means for your delivery. Throughout your pregnancy, your twin babies will move in the uterus, but sometime during the third trimester – usually between 32 and 36 weeks – their fetal presentation changes as they prepare to go down the birth canal.
The good news is that at most twin births, both babies are head-down (vertex), which means you can have a vaginal delivery. In fact, nearly 40% of twins are delivered vaginally.
But if one baby has feet or bottom first (breech) or is sideways (transverse), your doctor might deliver the lower twin vaginally and then try to rotate the other twin so that they face head-down (also called external cephalic version or internal podalic version) and can be delivered vaginally.
If that doesn't work, there's still a chance that your doctor will be able to deliver the second twin feet first vaginally via breech extraction (delivering the breech baby feet or butt first through the vagina). It depends on how experienced your doctor is in the procedure and how much the second twin weighs.
That said, you shouldn't totally rule out a C-section with twins. If the first twin is breech or neither of the twins are head-down, then you'll most likely have a Cesarean delivery.
Learn about the six possible twin fetal presentations: vertex-vertex, vertex-breech, breech-breech, vertex-transverse, breech-transverse, and transverse-transverse – and how they'll impact your delivery and risks for complications.
Key takeaways
- Twin fetal presentation – the position of your babies in the womb – can determine whether you'll have a vaginal or C-section birth.
- At the end of pregnancy, most twins will move in the head-down position (vertex), but there's a chance that they'll be feet or bottom first (breech) or sideways (transverse).
- Most of the time, you can have vaginal delivery if your babies are vertex-vertex. Other presentations can up the risk of a C-section.
Head down, head down (vertex, vertex)
This fetal presentation is the most promising for a vaginal delivery because both twins are head-down. Twins can change positions, but if they're head-down at 28 weeks, they're likely to stay that way.
When delivering twins vaginally, there is a risk that the second twin will change position after the delivery of the first. Research shows that second twins change positions in 20% of planned vaginal deliveries. If this happens, your doctor may try to rotate the second twin so it faces head-down or consider a breech extraction. But if neither of these work or are an option, then a Cesarean delivery is likely.
In vertex-vertex pairs, the rate of Cesarean delivery for the second twin after a vaginal delivery of the first one is 17%.
Like all vaginal deliveries, there's also a chance you'll have an assisted birth, where forceps or a vacuum are needed to help deliver your twins.
Head down, bottom down (vertex, breech)
When the first twin's (the lower one) head is down, but the second twin isn't, your doctor may attempt a vaginal delivery by changing the baby's position or doing breech extraction, which isn't possible if the second twin weighs much more than the first twin.
The rates of emergency C-section deliveries for the second twin after a vaginal delivery of the first twin are higher in second twins who have a very low birth weight. Small babies may not tolerate labor as well.
Head down, sideways (vertex, transverse)
If one twin is lying sideways or diagonally (oblique), there's a chance the baby may shift position as your labor progresses. Otherwise, your doctor may try to turn the baby head-down so you can deliver both vaginally.
Bottom down, bottom down (breech, breech)
When both twins are breech, a planned C-section is recommended because your doctor isn't able to turn the fetuses. Studies also show that there are fewer negative neonatal outcomes for planned C-sections than planned vaginal births in breech babies.
As with any C-section, the risks for a planned one with twins include infection, loss of blood, blood clots, injury to the bowel or bladder, a weak uterine wall, placenta abnormalities in future pregnancies, and fetal injury.
Bottom down, sideways (breech, transverse)
When the twin lowest in your uterus is breech or transverse (which happens in 25% of cases), you'll need to have a C-section.
Sideways, sideways (transverse, transverse)
This fetal presentation is rare, happening in less than 1% of cases. If both babies are lying horizontally, you'll almost definitely have a C-section.
