Multiple Pregnancies



Multiple pregnancies happen when:

  • A single egg divides and grows into two or more fetuses (identical)—babies will be same sex and look similar
  • More than one egg is fertilized by a different sperm (fraternal)—babies look different and may be different sexes

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

Risk Factors

Women over 30 are more likely to have a multiple pregnancy. It is also more common in women who have fertility treatments.

Other things that may raise the chances of having a multiple pregnancy are:

  • A past multiple pregnancy
  • A family history of multiple births
  • More than one past pregnancy



Symptoms are:

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


The number of fetuses can be found with routine prenatal tests. The doctor may suspect twins based on a person's history or symptoms. It can be confirmed with:

  • Ultrasound—can create images of fetuses
  • Fetal heartbeat—more than one heartbeat can be heard
  • Certain blood tests done near the 16th week of pregnancy—will show higher levels with more than one fetus



Regular prenatal visits will help keep the mother and babies well. Some problems that will be watched for are:

Early Labor

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

Gestational Diabetes

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


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

Fetal Position Issues (Breech or Transverse)

More than one fetus in the uterus raises the chance that one of them will be unable to turn head down. A breech or transverse presentation may require 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 not equal, TTTS can happen. 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 their heart beats 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 one fetus.

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


Multiple pregnancy with natural conception cannot 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.