A twin pregnancy carries specific risks and complications for both the baby and mother. The maternal-fetal medicine experts at Brigham and Women’s Hospital provide expert, multi-disciplinary care and are committed to doing everything possible to ensure the health of mothers and their babies.
The most common complication for a twin pregnancy is preterm delivery, a delivery that occurs before 37 weeks.
About half of all twin pregnancies are delivered around 36 weeks. This can cause low birth weight, as well as feeding and breathing difficulties for the twins. Unfortunately, there are limited treatment methods to prevent preterm delivery.
The clinical management of preterm delivery in twin gestation is complex. If your obstetric care provider is concerned that you may deliver your twins prematurely, several therapies can be discussed:
This device is a soft, flexible ring that is placed inside of the mother’s vagina by her obstetric care provider to help prevent preterm labor in those patients who are at higher risk, including those with a shorter cervix.
Very few studies have used the Arabin pessary in women with twin pregnancies and a short cervix to prevent preterm delivery. The results are difficult to generalize and validate; however, we recommend using this method for mothers who meet the right clinical requirements because it is non-invasive and not thought to cause harm to the fetus or mother.
Once the Arabin pessary is inserted, it does not need to be removed until delivery. It can cause a white, watery vaginal discharge that it is sometimes confused with rupture of membranes. The vaginal discharge is normal and there is no reason for concern.
Intrauterine growth restriction (IUGR) is a condition where an unborn baby grows more slowly than the normal rate. Twins are at a higher risk of IUGR, which can lead to a preterm delivery.
Your obstetric care provider can determine if your twins are affected with IUGR by serial growth ultrasounds.
If your obstetric care determines that one, or both twins, is not growing at the proper rate or falls below the 10th percentile on the growth curve for gestational age, you will need to increase the frequency of office visits and the surveillance of your babies with ultrasounds and fetal testing.
Mo-Di twins share a placenta, so it is likely that they share vascular connections. Unequal blood sharing in the vessels, occurring in about 15% of Mo-Di pregnancies, is called twin-to-twin transfusion syndrome (TTTS) and can be potentially dangerous.
This condition is sometimes difficult to distinguish from TTTS. When monochorionic twins differ in size by more than 20% this is most likely due to unequal sharing of the placenta. Those pregnancies with at least one growth-restricted fetus and twin growth discordance of more than 20% are at higher risk of neonatal morbidity. Pregnancies affected by twin growth discordance should have closer surveillance.
Twin reversal arterial perfusion syndrome (TRAP) is a rare condition that affects monochorionic twins (Mo-Di and Mo-Mo). With TRAP, one twin does not develop a normal heart and brain structures but receives blood supply from the other, normally developing twin. Because the normal twin must pump an excess amount of blood, this strains the twin’s heart and increases the risk of heart failure. If untreated, TRAP is a very serious condition.
Stopping the extra blood pumped between twins is the only way to treat this condition.
This is done with a small intrauterine minimally invasive surgery. Radiofrequency ablation is used inside the uterus to end the blood flow from the umbilical cord to the underdeveloped twin. With this technique, there’s a high chance that the normally developing twin will survive.
Mo-Mo twins share an amniotic sac, so it is common for their umbilical cords to become entangled during the pregnancy.
Entanglement increases the risk that the cords will compress and interrupt blood flow to one or both twins. This can cause unexpected and potentially life-threatening distress for one or both twins.
If carrying Mo-Mo twins, we recommend:
While carrying twins, you will have a larger placental size than a singleton pregnancy. A larger placenta produces more pregnancy hormones, which makes the occurrence of gestational diabetes more likely. It is very common and is usually temporary, resolving after pregnancy.
All pregnant women are screened for gestational diabetes in the third trimester, typically between 24-28 weeks. The screening test involves drinking a very sweet drink and then drawing your blood one hour later. You do not need to be fasting for the test.
If the screening test is positive, you will take a diagnostic test. This test is very similar to the initial test but you need to be fasting and your blood will be drawn 1, 2 and 3 hours after drinking the sweet drink.
If you are diagnosed with gestational diabetes, you will need to:
When carrying twins, you may be more likely to develop high blood pressure. This is defined as a systolic blood pressure equal or higher than 140 and a diastolic blood pressure equal or higher than 90. If combined with the spilling of protein in the urine, laboratory abnormalities or symptoms (for example, headache, visual changes and right upper-quadrant pain), this condition is called preeclampsia and it can be more serious.
If you are diagnosed with hypertension or preeclampsia, you will need to:
Gastroesophageal reflux disease, also known as GERD and heartburn, frequently affects mothers carrying twins.
Small changes in lifestyle and diet can lessen the severity effectively, including:
Pain or tingling in the leg—a condition called sciatica—and low-back pain are more common during a twin pregnancy but are not considered dangerous. If you experience this discomfort, consider:
We are happy to respond to general questions about twin pregnancies. Please use our online form to send us your twin pregnancy question, and one of our maternal-fetal medicine specialists will respond. Please note that your question will be emailed and responded through a private and secure system.
Learn about obstetric services provided by Brigham and Women’s Hospital.
Read more about maternal-fetal medicine at Brigham and Women’s Hospital.
Common questions and answers for women expecting twins from the American College of Obstetrics and Gynecology.
Social support organizations offer helpful information.
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