In this section
What is multiple pregnancy?
Multiple pregnancy is a pregnancy with two or more fetuses. Names for these include the following:
- Twins - 2 fetuses
- Triplets - 3 fetuses
- Quadruplets - 4 fetuses
- Quintuplets - 5 fetuses
- Sextuplets - 6 fetuses
- Septuplets - 7 fetuses
While multiples account for only a small percentage of all births (less than 3 percent), the multiple birth rate is rising. According to the National Center for Health Statistics, the twin birth rate has risen 49 percent since 1980, and is currently 28.1 per 1,000 live births. This is about one in every 36 live births. The birth rate for triplets and other higher order multiples has also risen a staggering 423 percent for that same time period to about one in 500 live births.
What causes multiple pregnancy?
There are many factors related to having a multiple pregnancy. Naturally occurring factors include the following:
- heredity - A family history of multiple pregnancy increases the chances of having twins.
- older age - Women over 30 have a greater chance of multiple conception. Many women today are delaying childbearing until later in life, and may have twins as a result.
- high parity - Having one or more previous pregnancies, especially a multiple pregnancy, increases the chances of having multiples.
- race - African-American women are more likely to have twins than any other race. Asian and Native Americans have the lowest twinning rates. Caucasian women, especially those over age 35, have the highest rate of higher-order multiple births (triplets or more).
Other factors that have greatly increased the multiple birth rate in recent years include reproductive technologies, including the following:
- Ovulation stimulating medications such as clomiphene citrate and follicle stimulating hormone (FSH) help produce many eggs, which, if fertilized, can result in multiple babies.
- Assisted reproductive technologies such as in vitro fertilization (IVF) and other techniques help couples conceive. These technologies often use ovulation stimulating medications to produce multiple eggs which are then fertilized and returned to the uterus to develop
How does multiple pregnancy occur?
Multiple pregnancy usually occurs when more than one egg is fertilized and implants in the uterus. This is called fraternal twinning and can produce boys, girls, or a combination of both. Fraternal multiples are simply siblings conceived at the same time. However, just as siblings often look alike, fraternal multiples may look very similar. Fraternal multiples each have a separate placenta and amniotic sac.
Sometimes, one egg is fertilized and then divides into two or more embryos. This is called identical twinning and produces all boys, or all girls. Identical multiples are genetically identical, and usually look so much alike that even parents have a hard time telling them apart. However, these children have different personalities and are distinct individuals. Identical multiples may have individual placentas and amniotic sacs, but most share a placenta with separate sacs. Rarely, identical twins share one placenta and a single amniotic sac.
Why is multiple pregnancy a concern?
Being pregnant with more than one baby is exciting and is often a happy event for many couples. However, multiple pregnancy has increased risks for complications. The most common complications include the following:
- preterm labor and birth - About half of twins and nearly all higher-order multiples are premature (born before 37 weeks). The higher the number of fetuses in the pregnancy, the greater the risk for early birth. Premature babies are born before their bodies and organ systems have completely matured. These babies are often small, with low birth weights (less than 2,500 grams or 5.5 pounds), and they may need help breathing, eating, fighting infection, and staying warm. Very premature babies, those born before 28 weeks, are especially vulnerable. Many of their organs may not be ready for life outside the mother's uterus and may be too immature to function well. Many multiple birth babies will need care in a neonatal intensive care unit (NICU).
- pregnancy-induced hypertension - Women with multiple fetuses are more than three times as likely to develop high blood pressure of pregnancy. This condition often develops earlier and is more severe than pregnancy with one baby. It can also increase the chance of placental abruption (early detachment of the placenta).
- anemia - Anemia is more than twice as common in multiple pregnancies as in a single birth.
- birth defects - Multiple birth babies have about twice the risk of congenital (present at birth) abnormalities including neural tube defects (such as spina bifida), gastrointestinal, and heart abnormalities.
- miscarriage - A phenomenon called the vanishing twin syndrome in which more than one fetus is diagnosed, but vanishes (or is miscarried), usually in the first trimester, is more likely in multiple pregnancies. This may or may not be accompanied by bleeding. The risk of pregnancy loss is increased in later trimesters as well.
- Twin-twin transfusion syndrome - Twin-twin syndrome is a condition of the placenta that develops only with identical twins that share a placenta. Blood vessels connect within the placenta and divert blood from one fetus to the other. It occurs in about 15 percent of twins with a shared placenta.
- abnormal amounts of amniotic fluid - Amniotic fluid abnormalities are more common in multiple pregnancies, especially for twins that share a placenta.
- cesarean delivery - Abnormal fetal positions increase the chances of cesarean birth.
- postpartum hemorrhage - The large placental area and over-distended uterus place a mother at risk for bleeding after delivery in many multiple pregnancies.
What is multifetal pregnancy reduction?
In recent years, a procedure called multifetal pregnancy reduction has been used for very high numbers of fetuses, especially four or more. This procedure involves injecting one or more fetuses with a lethal medication, causing fetal death. The objective of multifetal reduction is that by reducing the number of fetuses in the pregnancy, the remaining fetuses may have a better chance for health and survival. Consult your physician for additional information.
What are the symptoms of multiple pregnancy?
The following are the most common symptoms of multiple pregnancy. However, each woman may experience symptoms differently. Symptoms of multiple pregnancy may include:
- uterus is larger than expected for the dates in pregnancy
- increased morning sickness
- increased appetite
- excessive weight gain, especially in early pregnancy
- fetal movements felt in different parts of abdomen at same time
How is multiple pregnancy diagnosed?
Many women suspect they are pregnant with more than one baby, especially if they have been pregnant before. Diagnosis of multiple fetuses may be made early in pregnancy, especially if reproductive technologies have been used. In addition to a complete medical history and physical examination, diagnosis may be made by:
- pregnancy blood testing - Levels of human chorionic gonadotrophin (hCG) may be quite high with multiple pregnancy
- alpha-fetoprotein - Levels of a protein released by the fetal liver and found in the mother's blood may be high when more than one fetus is making the protein
- ultrasound - a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels - with a vaginal transducer, especially in early pregnancy, or with an abdominal transducer in later pregnancy.
Management of multiple pregnancy:
Specific management for multiple pregnancy will be determined by your physician based on:
- your pregnancy, overall health and medical history
- the number of fetuses
- your tolerance for specific medications, procedures or therapies
- expectations for the course of the pregnancy
- your opinion or preference
Management of multiple pregnancy may include the following:
- increased nutrition - Mothers carrying two or more fetuses need more calories, protein, and other nutrients, including iron. Higher weight gain is also recommended for multiple pregnancy. The American College of Obstetricians and Gynecologists recommends women carrying twins gain at least 35 to 45 pounds.
- more frequent prenatal visits (to check for complications and to monitor nutrition and weight gain)
- referrals - Referral to a maternal-fetal medicine specialist, called a perinatologist, for special testing or ultrasound evaluations, and to coordinate care of complications, may be necessary.
- increased rest - Some women may also need bedrest - either at home or in the hospital depending on pregnancy complications or the number of fetuses. Higher-order multiple pregnancies often require bedrest beginning in the middle of the second trimester.
- maternal and fetal testing - Testing may be needed to monitor the health of the fetuses, especially if there are pregnancy complications.
- tocolytic medications - Tocolytic medications may be given, if preterm labor occurs, to help slow or stop contractions. These may be given orally, in an injection, or intravenously. Tocolytic medications often used include terbutaline and magnesium sulfate.
- corticosteroid medications - Corticosteroid medications may be given to help mature the lungs of the fetus. Lung immaturity is a major problem of premature babies.
- cervical cerclage - Cerclage (a procedure used to suture the cervical opening) is used for women with an incompetent cervix. This is a condition in which the cervix is physically weak and unable to stay closed during pregnancy. Some women with higher-order multiples may require cerclage in early pregnancy.
How are multiple pregnancies delivered?
Delivery of multiples depends on many factors including the fetal positions, gestational age, and health of mother and fetuses. Generally, in twins, if both fetuses are in the vertex (head-down) position and there are no other complications, a vaginal delivery is possible. If the first fetus is vertex, but the second is not, the first fetus may be delivered vaginally, then the second is either turned to the vertex position or delivered breech (buttocks are presented first). These procedures can increase the risk for problems such as prolapsed cord (when the cord slips down through the cervical opening). Emergency cesarean birth of the second fetus may be needed. Usually, if the first fetus is not vertex, both babies are delivered by cesarean. Most triplets and other higher-order multiples are born by cesarean.
Vaginal delivery may take place in an operating room because of the greater risks for complications during birth and the need for cesarean delivery. Cesarean delivery is usually needed for fetuses that are in abnormal positions, for certain medical conditions of the mother, and for fetal distress.
Care of multiple birth babies
Because many multiples are small and born early, they may be initially cared for in a special care nursery called the neonatal intensive care unit (NICU). Once babies are able to feed, grow, and stay warm, they can usually be discharged. Other babies, that are healthy at birth, may need only a brief check in a special care nursery.
Breastfeeding multiples is certainly possible and many mothers of twins and even triplets are successful in breastfeeding all of their babies. Lactation specialists can help mothers of multiples learn techniques for breastfeeding their babies separately and together, and to increase their milk supply. Mothers whose babies are unable to breastfeed because they are sick or premature can pump their breast milk and store the milk for later feedings.
Families with more than one baby need help from family and friends. The first two months are usually the most difficult as everyone learns to cope with frequent feedings, lack of sleep, and little personal time. Having help for household chores and daily tasks can allow the mother the time she needs to get to know her babies, for feedings, and for rest and recovery from delivery.
Get a second opinion
Research and outcomes
Our outcomes reports help families and partner providers make the most informed healthcare decisions. Learn more about our surgical outcomes and current research studies.