It’s clear that twins in the womb who have to share their “home” with their other twin siblings have it much rougher than those who don’t.
After birth, the average weight of a set of twins is only about 2.2 kg (4.85 lbs), and the weight of a set of triplets or quadruplets is even less. Babies have plenty of room to “wiggle” and stretch out during the first 20 weeks of pregnancy.
However, beginning around week 28, as the amniotic sac and the mother’s uterus reach their maximum expansion, this space becomes increasingly congested. It’s not uncommon for twins to be in different places in the womb.
Either one or both infants may initiate the process of “coming out” by turning their heads, but this is not a guarantee.
When a fetus fails to turn to the optimal position for vaginal birth, doctors typically advise a cesarean section to protect the health of mother and child.