Merck Manual

Please confirm that you are a health care professional

honeypot link

Multifetal Pregnancy


Julie S. Moldenhauer

, MD, Children's Hospital of Philadelphia

Reviewed/Revised Jul 2021 | Modified Sep 2022

Multifetal pregnancy is presence of > 1 fetus in the uterus.

Multifetal (multiple) pregnancy occurs in up to 1 of 30 deliveries.

Risk factors for multiple pregnancy include


Multifetal pregnancy increases the risk of

  • Twins: 35 to 36 weeks

  • Triplets: 32 weeks

  • Quadruplets: 30 weeks

Fetal presentation may be abnormal. The uterus may contract after delivery of the first child, shearing away the placenta and increasing risk for the remaining fetuses. Sometimes uterine distention impairs postpartum uterine contraction, leading to atony and maternal hemorrhage Postpartum Hemorrhage Postpartum hemorrhage is blood loss of > 1000 mL or blood loss accompanied by symptoms or signs of hypovolemia within 24 hours of birth. Diagnosis is clinical. Treatment depends on etiology... read more .

Some complications develop only in multifetal pregnancies. An example is twin-twin transfusion syndrome (when twins share the same placenta; this syndrome results in vascular communication between the two, which can lead to unequal sharing of blood).


  • Prenatal ultrasonography

Multifetal pregnancy is suspected if the uterus is large for dates; it is evident on prenatal ultrasonography.


  • Cesarean delivery when indicated

Cesarean delivery Cesarean Delivery Cesarean delivery is surgical delivery by incision into the uterus. Up to 30% of deliveries in the US are cesarean. The rate of cesarean delivery fluctuates. It has recently increased, partly... read more is done when indicated. Cesarean delivery is recommended for twins unless the presenting twin is in vertex presentation. Higher-order multiples are typically delivered by cesarean regardless of presentation.

Key Points

  • In multifetal pregnancies, the overdistended uterus tends to stimulate preterm labor, resulting in preterm delivery.

  • Check for other possible complications, such as preeclampsia and gestational diabetes, and prepare for preterm delivery, cesarean delivery, and postpartum hemorrhage.

  • If the uterus is large for gestational age, do ultrasonography.

  • For most multifetal pregnancies, deliver by cesarean unless the presenting twin is in vertex presentation.

Drugs Mentioned In This Article

Drug Name Select Trade
Clomid, Serophene
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
quiz link

Test your knowledge

Take a Quiz!