Looking at most newborn twins squirm contentedly in their cribs, you'd never guess that some were recently in peril. That's because carrying multiples raises the risks that a woman can suffer complications before she actually delivers.
Many twins are miscarried early in the pregnancy, often before a woman even knows she's pregnant. As reported in the International Journal of Fertility, only about one in eight embryos that starts as a twin is born as a twin. If they do survive, twins are usually born healthy. However, they are still more likely than other babies to have birth defects or to be born prematurely or underweight.
Carrying twins can be hard on you, too. You'll be more likely to develop pregnancy-related high blood pressure or diabetes. And there's a greater likelihood you will have a cesarean section when you deliver.
If you're carrying twins, some simple lifestyle changes and good prenatal care may help you reduce the likelihood of the following complications.
According to the March of Dimes, more than 50 percent of all twins are born prematurely, which means they arrive before the 37th week of pregnancy. On average, twin pregnancies last only 35 weeks, or four weeks shorter than single pregnancies. Most babies born at 35 weeks will do just fine, requiring only some extra attention in the hospital nursery. But because premature babies are at higher risk for health problems, you should do what you can to prevent early delivery.
For starters, you can eat well; don't smoke, drink, or use illegal drugs; exercise at least 30 minutes a day on most, if not all, days of the week (with your doctor's permission); and take a daily prenatal vitamin that contains at least 30 milligrams of iron. Research also shows that reducing stress and avoiding working long hours on your feet may help reduce the risk of early delivery.
Low birth weight
Because they have to share nutrients and living space, newborn twins tend to be smaller than single babies. Even full-term twins often weigh less than 5-1/2 pounds each, making them vulnerable to a variety of health problems. You can help your babies reach a healthy size by making sure you put on enough weight during pregnancy. Try to eat 300 calories more each day than you would if you had a single baby (about 2,700 calories in total). If you had a healthy weight before pregnancy, you should aim to put on about 35 or 45 pounds.
Twins don't always share equally. In roughly 30 percent all twin births, one baby will be larger than the other. Some studies suggest that if one of your babies is at least 25 percent heavier than the other, one or both of them may be more likely to have breathing problems or need intensive care. Your doctor will track the growth of both your babies throughout your pregnancy. The first signs of unequal growth usually appear in the third trimester.
Twin transfusion syndrome
Twin transfusion syndrome poses a dangerous threat to identical twins who share a single placenta. It's normal for such twins to exchange blood during a pregnancy. But in about 20 percent of cases, one twin starts pumping large amounts of blood to the other twin, putting both of them at risk. In severe cases, the twin receiving the extra blood may develop heart failure while the other twin becomes dangerously anemic. Early diagnosis and treatment can slow the abnormal blood flow and lower the risk of complications.
Birth defects are common in twins, especially identical twins. Taking folic acid before and during pregnancy can help prevent neural tube defects. As reported in the medical journal The Lancet, however, about 10 percent of all identical twins are born with a birth defect such as a heart problem, a shortened limb, a club foot, or a dislocated hip (the conditions listed are linked to having less space in the uterus and would not be affected by folic acid.) Most of these conditions are treatable, however.
Risks to the mother
Your doctor will check you regularly throughout the pregnancy for signs of high blood pressure or diabetes. When detected early, both of these conditions can be controlled before they have a chance to threaten your pregnancy.
Carrying twins means you'll probably get extra attention from your doctor throughout your pregnancy. The doctor may suggest cutting back on activities between the 20th and 30th week of pregnancy, even if you haven't had any signs of labor. Many physicians also recommend an extra monitoring check on the babies' heart rate and movement, such as an ultrasound or nonstress test. A biophysical profile, which checks on heart rate, movement, and the amount of amniotic fluid in your body, might also be indicated. If you do go into labor prematurely, your doctor may suggest drugs to stop the labor or use corticosteroids to speed up the development of the babies' lungs.
It's possible that you may be able to deliver twins vaginally. But if the labor is difficult, the birth canal is too narrow, or one or both of the infants is in the breech position, you may have to undergo a c-section, in which the babies are delivered through an incision in your uterus. Talk to your doctor about what you can do to prepare for delivery.
Twins are a special challenge, both before birth and after. For now, your job is to stay healthy and get top-quality prenatal care. Two important people are counting on you.
March of Dimes. Multiples: Twins, triplets and beyond. December 2009. http://www.marchofdimes.com/professionals/14332_4545.asp
Hall J. Twinning. The Lancet. Vol. 362: 735-743.
Branum AM and KC Schoendorf. The effect of birth weight discordance on twin neonatal mortality. Obstetrics and Gynecology. Vol. 101(3):570-574.
Sherer DM. Adverse perinatal outcome of twin pregnancies according to chorionicity: review of the literature. American Journal of Perinatology. Vol. 18(1): 23-37.
Medem. Having Twins. American Congress of Obstetricians and Gynecologists.
American Congress of Obstetricians and Gynecologists. Exercise during Pregnancy. http://www.acog.org/publications/patient_education/bp119.cfm