The term multiple pregnancy refers to the presence of more than 1 fetus in the uterus (such as twins or triplets).
The number of twin, triplet, and other multiple pregnancies has increased due to use of assisted reproductive technologies to treat infertility. As many as 1 of 30 deliveries involves more than one fetus.
The following make women more likely to become pregnant with more than one fetus:
Using assisted reproductive technologies (such as in vitro fertilization)
Personal or family history of multiple births
A high number of previous pregnancies
Being age 35 years or over
Having obesity
Risks of Multiple Births
Carrying more than one fetus increases the risk of pregnancy complications.
Carrying more than one fetus overstretches the uterus, and an overstretched uterus tends to start contracting before the pregnancy reaches full term (preterm labor). As a result, the babies are usually born too early and are small. Risk of stillbirth or death is increased for preterm newborns. In some cases, the overstretched uterus does not contract well after delivery, causing bleeding in after delivery (postpartum hemorrhage).
Because the fetuses can be in various positions and presentations, vaginal delivery can be complicated. Also, the contraction of the uterus after delivery of the first baby may shear away the placenta of the remaining baby or babies. As a result, the baby or babies that follow the first may have more problems during delivery.
Carrying more than one fetus also increases the risk of pregnancy complications. They include
Hyperemesis gravidarum (extremely severe nausea and excessive vomiting during pregnancy)
Preeclampsia (high blood pressure plus protein in the urine)
Preterm labor and delivery
Diagnosis of Multiple Births
Ultrasound
Doctors suspect more than one fetus when the uterus is larger than expected for the length of the pregnancy. Ultrasound is done to confirm the number of fetuses.
Management of Multiple Births
Monitor for complications
Cesarean delivery, if needed
Because problems can result from multiple births, doctors may decide in advance whether to deliver vaginally or by cesarean.
For twins, if the first twin's position is head first (vertex), the first twin is usually delivered vaginally. The second twin, if not in an abnormal position or in distress, can usually be delivered vaginally. If the first twin is in an abnormal position or if the second twin in an abnormal position or in distress, cesarean delivery is used.
For triplets and other multiple births, a cesarean delivery is usually done.
