Twin Pregnancy Risks and Prematurity

Twin boys 5 days old together in hospital
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In This Article

A twin pregnancy comes with risks, both for the mother and the babies. Some moms hope to conceive twins or even higher-order multiples and will take active steps during fertility treatment to increase their odds. Other moms do what they can to avoid conceiving twins, but still get pregnant with more than one baby.

Understanding the risks of a twin pregnancy before you conceive can help you make decisions regarding your fertility treatment. For example, if your doctor offers a choice of transferring multiple embryos versus a single embryo during IVF treatment, you might be more willing to try a single embryo transfer (SET) if you know your risks.

Or, if your doctor doesn't even mention SET, you can ask if you're a good candidate for it, but only if you know your options. Understanding the risks of a twin pregnancy after you've already conceived twins is also important. For example, you can educate yourself on the signs and symptoms of premature labor, knowing prematurity is a risk with twins.

Not all risks are avoidable or within your control. Still, knowing what to watch out for can help reduce surprises along the way and increase your awareness of potentially troublesome symptoms.

Risks for the Mother

Twin pregnancy is not just risky for the babies, but also to the mother. However, many of the risks to the mother are also risks to the unborn babies, since they can lead to premature labor, complications, or in the worst cases, fetal death. Some of these risks are more of a nuisance than a real danger, while others can be life-threatening if left untreated.

Hypertension

Gestational hypertension is high blood pressure during pregnancy. In multifetal pregnancies (twins, triplets, or more), there is an increased incidence of hypertension. In a singleton pregnancy, the rate of hypertension is 6.5%; in twin pregnancies, it is almost double that at 12.7%.

Left untreated, gestational hypertension can lead to premature labor, babies who don't grow well, or stillbirth. It can also be a serious threat to the mother's health, especially if it develops into preeclampsia.

Preeclampsia

Preeclampsia is a condition that includes both high blood pressure and protein in the urine. Symptoms may include swelling, severe headache, and rapid weight gain. It is twice as likely to occur in mothers of multiples. If left untreated, preeclampsia can lead to eclampsia, also known as toxemia.

Eclampsia causes seizures and can be life-threatening to the mother and unborn babies. While blood pressure medications and anticonvulsant medications may stabilize the mother in severe cases, so the baby can spend a little more time in the womb, the only cure for preeclampsia is delivery of the baby.

Gestational Diabetes

Gestational diabetes is a condition where a person who was not diabetic prior to pregnancy has difficulty maintaining normal blood sugar levels. Gestational diabetes occurs in about 5% of singleton pregnancies, but women pregnant with twins are twice as likely to experience it.

Gestational diabetes can usually be treated with diet and lifestyle changes. However, some people do require medication to adequately control their glucose levels.

Hyperemesis Gravidarum

Intense morning sickness is more likely in women pregnant with twins. For some, this is more of a nuisance than a danger, but some may develop hyperemesis gravidarum. Hyperemesis gravidarum is severe morning sickness, which leads to a 5% loss in body weight for the mother and may require hospitalization.

Premature Labor

If premature labor begins, doctors may prescribe medications to stop labor. These may help prolong the pregnancy and allow the babies more time in the uterus. Prolonging the pregnancy also allows for the administration of steroids to help babies' lungs mature. These medications can have side effects, some mild and others more intense.

Cesarean Section

Cesarean section is more likely with multiples, due to unfavorable presentation (such as when the first baby is not head down) or complications, which means longer recovery for the mother after birth and a higher risk of complications during labor.

Other Risks

Moms of twins are more likely to experience gastrointestinal problems during pregnancy, like constipation. They also are more likely to experience problems with bleeding before or during delivery. And they may even experience postpartum depression.

Risks for the Babies

Twin pregnancies have a higher rate of miscarriage. In some cases, one twin may miscarry or simply "vanish," leaving a surviving twin. This is also known as vanishing twin syndrome.

Twins are at risk for intrauterine growth discordance, which is when one twin grows significantly slower than another. In identical twin pregnancies or pregnancies where twins share one placenta, this can be a sign of twin-to-twin transfusion syndrome (TTTS), where one twin takes more than its share of blood flow from the placenta.

TTTS occurs in 10% of monochorionic pregnancies. If left untreated, severe TTTS can lead to infant heart failure or death of one or both twins.

Twins are more likely to have low birth weights, even when they are born on time. Twins are also more likely to become jaundiced.

Risk of Prematurity

Twin pregnancies have a higher risk for prematurity, which means birth that occurs after 20 weeks but before 37 weeks gestation. Just 40% of twin pregnancies go full term. The average twin pregnancy is 35 weeks, compared to the average singleton pregnancy, which is 39 weeks. Prematurity may lead to a number of problems, including:

  • Immature lungs, leading to difficulty in breathing. Premature babies may be put on ventilators until the lungs mature.
  • Stomach and intestinal tract problems
  • Nervous system problems, including bleeding in the brain
  • Low birth weight
  • Feeding problems, including difficulty with breastfeeding

Thanks to advances in technology, 90% of infants born after 28 weeks survive. However, even babies who survive prematurity are at risk for long-term effects.

Long-Term Complications of Prematurity

  • Bronchopulmonary dysplasia (BPD), a chronic lung condition that may require oxygen support for weeks or months after birth
  • General respiratory problems, including a higher likelihood of developing asthma and respiratory infections
  • Developmental delays
  • Learning disabilities, and in severe cases, retardation which may not become evident for years
  • Cerebral palsy
  • Vision problems
  • Hearing loss

Premature birth is also difficult for the parents, who go through the stress of having the babies in the NICU for days, weeks, or months, depending on how early the babies are born and what complications occur. Not being able to take your baby home can be very upsetting, and seeing your baby hooked up to the NICU equipment can be heartbreaking.

Have a Healthy Twin Pregnancy

You can’t eliminate the risks of a twin pregnancy, but there are steps you can take to reduce those risks. They include...

  • Get regular prenatal care. The sooner any problems are caught, the better care you can receive. Getting regular prenatal care, ideally with a doctor with experience with twin pregnancies, is essential.
  • Eat well. Your diet can have a big impact on your pregnancy and your twins. Research has found that adequate weight gain during a twin pregnancy can help ensure the babies are born at a healthier weight. You want to be sure your diet has a good amount of protein as well, to help grow those babies.
  • Stay hydrated. Dehydration can trigger premature labor in any pregnancy. In a twin pregnancy, your risk may be higher. If you’re thirsty, drink!
  • Don’t put yourself on bed rest. Your doctor may place you on partial or strict bed rest at some point in your pregnancy, if there are complications warranting it. However, don’t put yourself on bed rest without reason. There are risks to bed rest, and there’s no benefit if it’s done out of routine. 
  • Know the signs and symptoms of premature labor. If ignored, labor may progress to a point where things can't be stopped. However, if the signs and symptoms are caught early enough, it may be possible to delay birth by weeks or even months. Every day in the womb gives the babies lungs and body time to develop.

A Word From Verywell

There are risks to twin pregnancies, for both the mom and baby. However, good prenatal care can help reduce some of these risks. Talk to your doctor about any concerns, and advocate for yourself and your babies.

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Article Sources
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  2. Da Silva Lopes K, Takemoto Y, Ota E, Tanigaki S, Mori R. Bed rest with and without hospitalisation in multiple pregnancy for improving perinatal outcomes. Cochrane Database Syst Rev. 2017;3:CD012031. doi:10.1002/14651858.CD012031.pub2

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