Condition Basics
What is a multiple pregnancy?
A multiple pregnancy means that there are two or more babies in the uterus. A pregnancy of twins or more is considered to be high-risk. Problems are more common in multiple pregnancies than in pregnancies of one fetus (singleton pregnancy).
The babies in a multiple pregnancy may be identical or fraternal.
Identical siblings
Babies that come from the same egg are called identical. This happens when one egg is fertilized by one sperm, and the fertilized egg then splits into two or more embryos.
Experts think that the process that results in identical siblings happens by chance. It isn't related to the parents' age, race, or family history.
If the babies you're carrying are identical, the siblings:
- Are all of the same sex, either all boys or all girls.
- All have the same blood type.
- Probably will have the same body type and the same color skin, hair, and eyes. But they may not look exactly the same. They also won't have the same fingerprints.
Fraternal siblings
Babies that come from different eggs are called fraternal. This happens when two or more eggs are fertilized by different sperm.
Fraternal twins tend to run in families. This means that if anyone in your family has had fraternal twins, you're more likely to have them too.
If the babies you're carrying are fraternal, the siblings:
- May be of different sexes.
- May have different blood types.
- May look different from each other or may look the same, as some brothers and sisters do.
What makes a multiple pregnancy more likely?
You are more likely to have a multiple pregnancy if you take fertility drugs or have in vitro fertilization. Other things that increase your chance of a multiple pregnancy include being age 35 or older or having fraternal twins on your side of the family.
What are the risks of a multiple pregnancy?
Any pregnancy has risks. But the chance of having problems is higher in a multiple pregnancy, and the risk increases with each extra baby you carry at the same time.
Being pregnant with more than one baby raises the risk of problems such as:
- High blood pressure and preeclampsia.
- Gestational diabetes.
- Preterm labor, which may lead to premature (preterm) birth. Preterm birth increases the babies' risk of lung, brain, heart, and eye problems.
- Miscarriage.
- Having a baby with a genetic condition or birth defect.
These problems may not happen to you. Many people have healthy multiple pregnancies and deliver healthy babies.
What are the symptoms?
You can expect to have the same symptoms during a multiple pregnancy that you'd have during a pregnancy with one fetus. But the symptoms may happen earlier and may be worse. For example, a multiple pregnancy may cause early or severe morning sickness.
How can you tell if you're carrying more than one baby?
A fetal ultrasound can show how many babies are in your uterus. Your doctor can also use the ultrasound to check the health and growth of the babies.
What prenatal exams and tests will you need?
Your doctor will do a physical exam at each visit. The doctor may also do a fetal ultrasound, check your blood pressure, and test your blood and urine for any signs of problems. If problems are found, early treatment can help you and your babies stay healthy.