Multiple Pregnancy Complications

A multiple pregnancy (twins, triplets or higher-order multiples) carries specific risks and complications for both the babies and mother. The maternal-fetal medicine (MFM) specialists at the Comprehensive Care Center for Multiples at the Brigham provide expert, multidisciplinary care and will do everything possible to ensure the health of you and your babies.

My pregnancy was complicated by the type of twins I was carrying, Mo-Di twins. My baby A was growth restricted combined with cord flow/placental issues early on in the pregnancy that lead us to believe that he would not make it. Thankfully both [babies] are here and healthy...thanks to Dr. Bibbo and the entire team of nurses, sonographers, radiologists, etc.” - Christina, patient

The team of providers at the Brigham’s Comprehensive Care Center for Multiples are experts in multiple pregnancy and are prepared to care for you and your babies if any complications arise. Watch the above video to learn more.

Common Fetal Complications

Preterm Delivery

The most common complication for a multiple pregnancy is preterm delivery, a delivery that occurs before 37 weeks. This can lead to an infant with low birth weight along with feeding and breathing difficulties. Unfortunately, there are no medical interventions to prevent preterm delivery in a multiple gestation.

Women carrying one baby (singleton pregnancy) usually deliver by 40 weeks. Women carrying twins on average deliver around 36 weeks. For each additional baby, one can account for another month of prematurity, with most women carrying triplets delivering around 32 weeks and those of quadruplets delivering around 28 weeks.

Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is a condition in which an unborn baby is estimated to weigh less than expected for a particular gestational age (according to standardized charts for singleton babies, not multiples). This condition is detected with a growth ultrasound and classically defined when the estimated weight falls below the 10th percentile.

Multiples are at higher risk of IUGR because of placental crowding. One or all of the babies being smaller than expected is common in a multiple pregnancy.

In most cases, IGUR is mild and does not lead to any complications. In some cases, it is more serious and leads to a preterm delivery with complications for the newborns. The earlier the gestational age at delivery, the higher the degree of complications.

If your pregnancy is complicated by growth restriction of one of your babies, you will need to increase the frequency of office visits and monitoring of the pregnancy with antenatal testing.

Antenatal testing refers to testing that occurs before birth to evaluate the well-being of the babies in the late third trimester of pregnancy. It involves ultrasound and external electronic fetal heart rate monitoring.

Twin-to-Twin Transfusion Syndrome

Monochorionic diamniotic (Mo-Di) twins share one placenta. They also share connections of blood vessels along the placenta. When these connections are unbalanced, it leads to one twin having more volume than the other. This is called twin-to-twin transfusion syndrome (TTTS), which occurs in about 9–15% of Mo-Di twins.


TTTS is diagnosed using ultrasound that measures the twins' amniotic fluid volume. If one twin has very little amniotic fluid (oligohydramnios) and the other twin has extra amniotic fluid (polyhydramnios), TTTS is confirmed. The twin with little amniotic fluid (and sometimes smaller size) is called the donor twin. The twin with extra amniotic fluid is called the recipient twin.

How This Happens

The donor twin has less blood volume and thus produces less urine than usual. This causes a low level of amniotic fluid and a small bladder.

Due to increased blood flow, the recipient twin produces more urine than usual. This causes an excessive build-up of amniotic fluid. It can also lead to accumulation of extra fluid around the heart, a form of heart failure, or fluid accumulation in other parts of the body (e.g., abdomen or lungs) called hydrops.

TTTS Staging

TTTS is classified in five progressive stages, and the progression of TTTS can be unpredictable. However, most cases stay in stage I with fluctuating levels of amniotic fluid. Survival rates vary from 15 to 70%, depending on the twins' age at diagnosis and the severity of the condition.

Managing TTTS

A minimally invasive surgical procedure called fetoscopic laser photocoagulation is considered the best available treatment for twins with stages II, III or IV of TTTS before 26 weeks. This procedure disrupts the vascular connections between the twins. It is offered only at specialized fetal treatment centers.

Amnioreduction removes excess amniotic fluid from the recipient twin. This procedure may help alleviate the mother's discomfort caused by the extra fluid. Amnioreduction can be done in cases of TTTS when the patient is not a candidate for fetoscopic laser photocoagulation.

Careful supervision (often referred to as "expectant management") is needed throughout the pregnancy, even if a procedure is not required.

Delivering Twins With TTTS

The best time to deliver twins with TTTS depends on a number of factors, including disease stage and severity, progression, effect of interventions and results of antenatal testing.

Selective Growth Restriction

Selective growth restriction is sometimes difficult to distinguish from TTTS. It is diagnosed when monochorionic twins differ in size by more than 20% and one of the twins is growth-restricted.

This condition, which is diagnosed by ultrasound, occurs due to unequal placental sharing. The smaller twin receives nutritional supplies from a very small portion of the placenta, while the larger twin has access to the majority of the placenta.

Monochorionic twins with this condition are at higher risk of fetal distress and thus preterm delivery. Such pregnancies should be monitored very closely.

Twin Anemia Polycythemia Sequence

Twin anemia polycythemia sequence (TAPS) is a rare condition that affects 3–5% of monochorionic twins and about 10% of monochorionic twins that had undergone a fetoscopic laser procedure for treatment of TTTS.

This condition is similar to TTTS in that it occurs from the unbalance in vascular connections between the twins. These connections are much smaller and lead to chronic slow passage of red blood cells from one twin to the other. The donor twin has too few red blood cells, thus becoming anemic (thin blood), while the recipient twin has too many red blood cells (thick blood).

Cord Entanglement With Mo-Mo Twins

Monochorionic monoamniotic (Mo-Mo) twins share an amniotic sac, so it is common for their umbilical cords to become entangled during the pregnancy. This entanglement increases the risk that the cords will become compressed and that blood flow to one or both twins will be interrupted. This can cause unexpected and potentially life-threatening distress for one or both twins.

If you are carrying Mo-Mo twins, we recommend admission to the hospital between 24 to 28 weeks for daily surveillance with antenatal testing by MFM specialists.

Common Maternal Complications

Gestational Diabetes

Women carrying multiples have a larger placental size than those with a singleton pregnancy. A larger placenta produces more pregnancy hormones, which makes the occurrence of gestational diabetes more likely. This condition is temporary, resolving after pregnancy.

All pregnant women are screened for gestational diabetes in the third trimester, typically between 24 and 28 weeks. The screening test involves a sweet drink and then having your blood drawn one hour later. You should not be fasting for the test.

If the screening test is positive, you will have a diagnostic test. In this case, you will need to be fasting and have your blood drawn one, two and three hours after drinking the sweet drink.

If diagnosed with gestational diabetes, medical therapy may be required to control your blood sugars. In addition, you will need to:

  • Monitor your glucose levels at least four times per day.
  • Consult with a nutritionist to manage your diet and exercise.
  • Increase the frequency of office visits and surveillance of your babies with antenatal testing.

You may also need to consult with an MFM specialist.

Hypertensive Disorders

When carrying multiples, you may be more likely to develop high blood pressure. If combined with the spilling of protein in the urine, laboratory abnormalities or certain symptoms (e.g., headache, visual changes and right upper-quadrant pain), this condition is called preeclampsia and can be more serious.

If diagnosed with hypertension or preeclampsia:

  • You will need to increase the frequency of office visits and antenatal testing.
  • You may need to consult with an MFM specialist.
  • You may require antihypertensive medication, hospitalization and/or early delivery.


Anemia is a medical condition for which the count of healthy red blood cells is low. (Red blood cells carry oxygen to organs and tissues.)

Women carrying multiples have a higher risk of developing anemia due to greater nutritional demands. If you have anemia, you will generally feel tired and weak. Most cases are mild and due to a lack of iron in your diet. This can be easily treated with iron supplements. These supplements can cause constipation, so it is important to also take a stool softener if needed.

Gastroesophageal Reflux Disease (Heartburn)

Gastroesophageal reflux disease (GERD), commonly known as heartburn, frequently affects women carrying multiples.

Small lifestyle and diet changes like these can lessen the severity of symptoms:

  • Eating your last meal of the day at least three hours before bedtime
  • Elevating your head during sleep
  • Avoiding dietary triggers
  • Taking an antacid approved by your obstetric care provider

Sciatica and Low-Back Pain

Sciatica (pain or tingling in the leg) and low-back pain are more common during a multiple pregnancy but not considered dangerous. If you experience either of these problems, consider:

  • Wearing shoes with good arch support
  • Asking for help lifting heavy objects
  • Picking up lighter objects carefully by squatting down, lifting your knees and keeping your back straight
  • Placing a board between the mattress and box spring if your bed is too soft
  • Sitting in chairs with good back support or using a small pillow to provide additional support
  • Sleeping on your side with pillows between your knees for additional support
  • Massaging or applying heat or cold to the painful area
  • Taking pain relievers such as acetaminophen to lessen severe pain

For More Information

Please use our online form to submit any general questions you have about multiple pregnancies. One of our MFM specialists will follow up with you. Please note that your question will be emailed and responded to through a private and secure system.

You can also visit our Resources page for a wealth of resources for parents expecting multiples.

Learn more about Brigham and Women's Hospital

For over a century, a leader in patient care, medical education and research, with expertise in virtually every specialty of medicine and surgery.

About BWH