Twins in Utero  

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A multiple pregnancy is when a woman is pregnant with two or more fetuses. Twins are the most common type of multiple pregnancy. So-called “higher-order” pregnancies (when a woman is carrying triplets, quadruplets, quintuplets, or more) are less common.

The risk for certain complications during and after pregnancy is higher in multiple pregnancies. To lessen these risks your doctor will see you more often than a woman carrying one baby.



Multiple pregnancies occur when a single fertilized egg divides and develops into two or more fetuses (identical twins) or when more than one egg is fertilized by a different sperm (fraternal twins). Triplets, quadruplets, and quintuplets can be identical, fraternal, or a combination of both.


Risk Factors  

A risk factor is something that increases your chances of getting a disease or condition. The following factors increase your chance of having a multiple pregnancy. If you have any of these risk factors, tell your doctor:

  • Use of fertility treatments
  • A previous multiple pregnancy
  • A family history of multiple births
  • More than one previous pregnancy
  • African-American race
  • Older age


If you experience any of these symptoms do not assume it is due to a multiple pregnancy. These symptoms may be caused by other health conditions. If you experience any one of them, see your physician.

Symptoms include the following:

  • More rapid weight gain than expected in the first trimester
  • Larger than expected uterus
  • Severe morning sickness
  • More fetal movement than with a singleton pregnancy


Your doctor will ask about your symptoms and medical history, and perform a physical exam. Your doctor may refer you to a healthcare professional who has experience with multiple pregnancies.

Most multiple pregnancies are discovered during an ultrasound examination. An ultrasound examination is a test that uses sound waves to see how the fetus is developing. An ultrasound can detect more than 95% of multiples by the second trimester of pregnancy.

Other tests that may detect a multiple pregnancy include:

  • An abnormal result on certain blood tests done near the 16th week of pregnancy
  • Hearing more than one heart beat during a routine examination


Multiple pregnancies have a greater risk for certain complications. If you experience any of these conditions, your doctor will discuss the best treatment plan for you.

Preterm Labor  

Most multiple births are preterm (before the end of 37 weeks of pregnancy). Babies born preterm have a higher risk for many health problems. To delay preterm birth, your doctor may suggest bed rest at home or in a hospital or prescribe certain drugs. If labor threatens to occur before 34 weeks of pregnancy you may be g