It’s twins! Those words can fill parents with both excitement and trepidation. From a medical standpoint, expecting twins moves your pregnancy into the high-risk category. The only way to diagnose twins is by sonogram.
There are two types of twins – fraternal and identical. Fraternal twins come from two individual eggs. Each twin has its own fetal sac and placenta and is no more alike than any other siblings.
Identical twins are from a single egg that splits to form two babies. Identical twins are genetically the same. Occasionally, identical twins share a placenta, but they normally have their own fetal sac. Other multiple pregnancies, such as triplets, can be fraternal, identical, or a combination of the two.
About 3% of pregnancies are twins or triplets. Multiple gestation pregnancy is more come in women over age 35, African ancestry, a family history of fraternal twins, or fertility medications. Twin pregnancies are also more likely to be affected by gestational diabetes and pregnancy-associated hypertension.
Early in the pregnancy, each baby grows independent of the other twin. In the second half of the pregnancy, both babies begin to share resources, and delayed growth is typical and expected. However, occasionally one baby grows at the expense of the other twin. Therefore, frequent ultrasounds are used to keep track of the growth of each baby.
Preterm delivery is also a common outcome with multiple gestation pregnancies. The management of preterm labor often includes medicines to stop labor, bed rest, and hospitalization. Delivery before 35 weeks usually requires newborns to be admitted to the neonatal intensive care unit (NICU). If preterm delivery can be avoided, delivery at 37 weeks is commonplace with a twin pregnancy.
Cesarean section is more common in twin pregnancies. The commonest reason is a breech presentation of one or both babies. Even if the first baby delivers vaginally, the second twin still may require C-section. As a result, twins are often delivered in an operating room if an attempt at a vaginal delivery results in a cesarean section instead.