Multiple Pregnancies



A multiple pregnancy is when a woman is pregnant with 2 or more fetuses. Twins are the most common type of multiple pregnancy.

This type of pregnancy can have a higher risk of problems during and after pregnancy. A care team can help to decrease these risks.

Twins in Utero
si55551809 96472 1
Copyright © Nucleus Medical Media, Inc.


Multiple pregnancies occur when:

  • Single egg divides and develops into 2 or more fetuses (identical)—babies will be same sex and look similar
  • More than 1 egg is fertilized by a different sperm (fraternal)—babies look different and may be different sexes

If there are 3 or more fetuses they may be identical, fraternal, or both.

Risk Factors

Women over 30 are more likely to have a multiple pregnancy.

Factors that may increase your changes of having a multiple pregnancy include:

  • Use of fertility treatments
  • A previous multiple pregnancy
  • A family history of multiple births
  • More than 1 previous pregnancy



Symptoms include the following:

  • More rapid weight gain than expected in the first trimester
  • Severe morning sickness
  • More fetal movement than with a single fetus pregnancy


The number of fetuses can be found with normal prenatal tests. The doctor may suspect twins based on your history or symptoms. It can be confirmed with :

  • Ultrasound—can create images of fetuses
  • Fetal heartbeat—more than 1 heart beat can be hear during a routine exam
  • Certain blood tests done near the 16th week of pregnancy—will show higher levels with more than 1 fetus

You may be referred to a specialist.



Pregnancy itself does not need treatment. Your care team will watch for possible problems. Regular visits with your care team will help to keep the mother and baby well.

Potential problems that will be watched for include:

Early Labor

Most multiple births will end before 37 weeks of pregnancy. Babies born preterm have a higher risk for many health problems. Bed rest or medicine may help to delay early birth. Medicine may also be given to help the baby's lung mature if labor may start before 34 weeks of pregnancy.

Gestational Diabetes

Gestational diabetes is a high level of blood glucose during pregnancy. It can affect both the mother and baby's health. Treatment can help to return blood glucose levels to normal. It may include changes in diet, exercise, blood glucose level testing, and medicine.


Preeclampsia is a fast and dangerous increase in blood pressure during pregnancy. Treatment may include medicine, rest, and delivery of the babies.

Abnormal Fetal Position (Breech or Transverse)

More than 1 fetus in the uterus increases the chance that 1 of them will be unable to turn head down. A breech or transverse presentation increases the chance of needing a cesarean delivery.

Twin Twin Transfusion Syndrome (TTTS)

TTTS may happen with identical twins. Fetuses can share a tube to the placenta. If this sharing is unequal, TTTS can develop. One twin gets less blood. The other may end up with too much blood and fluid in the body. It can affect the health of both babies. Fetus growth and heart beat will be closely watched.

Fetal Growth

Multiple fetuses are more likely to have growth issues. Sometimes, one may be much smaller than the other. This can be normal or signal a problem. Growth will be carefully watched.


The risk of c-section is higher with more than 1 fetus.

Women will also have a higher chance of heavy blood loss after giving birth.


Multiple pregnancy with natural conception can not be prevented. Fertility treatments can lead to a multiple pregnancy. The care team will work to make sure the number of possible pregnancies is safe.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.

a (Twins; Triplets; Quadruplets; Quintuplets)


American Congress of Obstetricians and Gynecologists 

March of Dimes 


Health Canada 

The Society of Obstetricians and Gynaecologists of Canada 


American College of Obstetricians and Gynecologists (ACOG), Society for Maternal-Fetal Medicine. ACOG Practice Bulletin No. 169: Multifetal gestations: twin, triplet, and higher-order multifetal pregnancies. Obstet Gynecol 2016 Oct;128(4):e131, reaffirmed 2016.

Multiple gestation. EBSCO DynaMed Plus website. Available at: . Updated November 26, 2018. Accessed January 8, 2019.

Multiple pregnancy. American College of Obstetricians and Gynecologists website. Available at: Published July 2015. Accessed January 8, 2019.