Tamara Buechler, a physician at the Mayo Clinic, understands better than most expectant mothers the risks of delivering twins two months before they are due. But, when she was expecting, Buechler knew that she might not have a choice. Halfway into what she had hoped would be an uneventful pregnancy three years ago, her doctors diagnosed a cluster of severe complications — including a rare liver disease that occurs only in pregnancy and a cervix too weak to contain her twins. They warned the twins might not survive.
Buechler vowed not to lose them. But with every setback, she found herself saying goodbye. It's a dread shared by many expectant mothers whose pregnancies are high risk. Nearly half a million, or one out of nine, babies in the United States are born prematurely every year, according to the Centers for Disease Control and Prevention. A baby is considered premature if delivered before 37 weeks of pregnancy. Because their organs have not had enough time to develop, premature babies face a greater risk of severe complications, such as brain hemorrhages; vision and hearing loss; intellectual disabilities and infections, even death. A baby born between 34 weeks and 36 weeks has a three-fold to six-fold chance of dying within the first year, compared to babies who are born at full term.
[Premature births are so common, and so raise so many questions, that U.S. News will host a #Preemies Twitter chat May 23, 2013, from 2 p.m. to 3 p.m. Eastern to explore the latest developments and share personal stories. Details below.]
Much about prematurity remains a mystery, says Louis Muglia, co-director of the Perinatal Institute in the division of neonatology at Cincinnati Children's Hospital Medical Center. About half of premature births are unexplained; many of those occur without warning. About 25 percent to 40 percent are caused by infections, some of which are detectable and some of which are not, Muglia says. Research shows that genetic factors account for at least a third of the variation in the timing of a baby's birth. Genetic factors appear to play a role, too, in the risk of preterm birth. Mothers who have had one premature delivery, or were themselves born premature, are more likely to have a premature birth.
Preventing premature births is difficult, at best. "For many years there have been recommendations for different kinds of preventative care," Muglia says, "but most have proven ineffective." He cites examples such as getting more rest, taking antibiotics and quitting smoking. Though smoking is considered a risk factor for premature births, the data have shown no correlation, he says. Alcohol and drugs are also risk factors. In about 20 percent to 25 percent of cases doctors need to induce delivery because of concerns for the mother's health. For example, if a mom has blood poisoning she risks both her health and the health of her baby. Doctors sometimes prescribe progesterone supplements, which sometimes works in women who have had preterm births or women whose cervix is short.
Having twins increases the risk of premature delivery. Nearly 60 percent of twins are delivered early, but the conditions leading up to Buechler's delivery were particularly stressful. Severe fatigue and nausea told her something was wrong. Twenty-two weeks in came her diagnoses. An ultrasound revealed her weak cervix and bulging membrane, indicating a high likelihood of miscarriage. As a last resort, she decided to have her cervix stitched shut, a procedure that carries a high risk of rupturing and infection. Even then the babies risked being born early or getting sick.
"For me it was an easy decision because I knew they were going to die if I didn't [act]," she says. After the procedure she was sentenced to bed rest for 10 weeks. Some mothers would welcome time off their feet, she says, but she received little rest because she worried the whole time whether they were going to make it. Before the procedure, a neonatologist had said the prognosis was grim for both babies, and that the odds were especially low for the boy, who, due to his gender and low birthweight, had just a one percent chance of surviving.