What You Should Know About Twin Pregnancies

In this article, we will review some of the common pregnancy and birthing complications to understand how, if at all, a twin pregnancy is riskier.

 By Halle Tecco, MBA, MPH

Are you pregnant with twins, or trying to increase your chance of having twins? You may hear from your doctor, friends, or online that twin pregnancies are “riskier.” But what does that mean? What is the actual data? In this article, we will review some of the common pregnancy and birthing complications to understand how, if at all, a twin pregnancy is riskier.

The rate of gestational diabetes is 3.98% for twins (vs. 2.32% for singletons)

You may hear that your chances of gestational diabetes mellitus (GDM) are increased with twins, and that’s true; however, the prevalence is still under four percent. GDM is a pregnancy-related condition that prevents the body from effectively using insulin to control blood sugar levels. 

A 2009 study of 23,056 pregnant women found that the prevalence of GDM to be 3.98% for women pregnant with twins, compared to 2.32% for women pregnant with singletons. The study also found that women between the ages of 25 and 30 years and African-American women had the highest risk of developing GDM in twin pregnancies. 

Other risk factors for GDM include being overweight, having a family history of diabetes, PCOS, and lack of physical activity. You may be able to lower your risk of GDM by getting enough exercise and following a healthy diet; however, it's not clear whether this also prevents complications during pregnancy and childbirth. Talk to your doctor if you are at risk for GDM.

The rate of preeclampsia is 11.8% for twins (vs. 3.4% for singletons)

A 2019 epidemiological study from Norway found that the risk of preeclampsia in twin pregnancies was three to fourfold compared with singleton pregnancies, regardless of maternal age, parity, educational level, smoking, maternal comorbidity, or use of IVF. 

Preeclampsia is a pregnancy complication diagnosed in women with previously normal blood pressure, who after 20 weeks of gestation show a systolic blood pressure of 140 mm Hg or higher, or a diastolic blood pressure of 90 mm HG or higher along with proteinuria, or protein in the urine. 

There may be ways to reduce your risk of preeclampsia. According to WHO, vitamin D may reduce the risk of preeclampsia, low birthweight, and preterm birth, although more research is warranted. In addition, a baby aspirin (81 mg) taken daily may be recommended if you have risk factors for preeclampsia. Consuming baby aspirin daily may reduce the chance of preeclampsia developing.

Twins are generally born earlier

Fifty-nine percent of twins are born before 37 weeks; in fact, the majority of twin pregnancies now deliver at 34 to 36 weeks of gestation. While the average gestational age for twins at birth is 35.04 weeks, the average age for singletons is 38.51 weeks. This can sometimes be a problem requiring a stay in the NICU. But it can be helpful to know that for twins born after 28 weeks, neonatal death and severe long-term morbidity are rare.

What week of pregnancy are twins born?

About half of twin babies are born preterm, but every week matters, and “preterm” differs greatly amongst the sub categories:

• “Full Term:” 37+ weeks (50% of twins)
• "Late preterm:" 34-36 weeks (30%)
• "Moderately preterm:" 32-34 weeks (10% of twins)
• "Very preterm:" 28-32 weeks (5.9% of twins)
• "Extremely preterm:" before 28 weeks (4.1% of twins)

Only about five percent of babies born at 36 weeks are admitted to the NICU, and almost 30% experience some degree of respiratory distress. Infant mortality for babies at 36 weeks, after accounting for babies with undetected heart abnormalities, is around 0.8%. Extremely preterm births represent approximately 0.2% of singleton births and 4.1% of twins births. Survival rates for infants born at 28 weeks gestation are between 80-90%. And babies born at 28 weeks old only have a 10% chance of having long-term health problems.

Medicine is amazing— the survival rate in the US for 24-week-old infants is 60-70%. But, a 24-week old preemie’s chance of dying or having long-term health problems goes down dramatically if a woman can stay pregnant for just two or three weeks longer. This is why twin pregnancies require more prenatal care visits, so providers can keep a closer eye on their progress.

Twenty-three percent of twin pregnancies have a c-section, compared to 19.4% of singletons

Cesarean (c-section) rates differ greatly amongst providers, but a 2019 study found that twin pregnancies appear to be an independent risk factor for cesarean births. In fact, 23% of twin pregnancies were c-section compared to 19.4% for singletons. Read all about c-sections here.

Deciding how to birth your baby is no small feat and requires consideration of multiple factors. Make a point to actively engage both your support person(s) and your OBGYN to ensure you’re making the best decision considering your particular risks and likelihood of success. 

Prenatal health starts with your prenatal vitamin

In addition to your regular prenatal vitamin, doctors recommend increased intake of magnesium,calcium, zinc and  folate with twins. Demands for folate increase during pregnancy because it is required for growth and development of the fetus. Folate deficiency has been associated with abnormalities in both mothers (anemia, peripheral neuropathy) and fetuses (neural tube defects). For pregnant women, the recommended daily dose is 600-1,000 micrograms (mcg). For women pregnant with twins, the dosage increases to 1,000 mcg a day. 

Having a healthy twin pregnancy

There’s a lot to stress over with any pregnancy, but it’s important to remember that most women can— and do— have perfectly healthy twin pregnancies! If you’re carrying twins, you’ll want to talk to your doctor about diet, exercise, and rest. Like any pregnancy, you’ll want to avoid drinking, smoking, and drugs. Continue to educate yourself and understand the signs and symptoms of pregnancy conditions (like preeclampsia) and preterm labor. Wishing you all the best!