Published: Mar. 23, 2010
Updated: Mar. 23, 2010
By June Spence
One of the most curious and disturbing trends in American health is preterm births, which are on the rise in the United States -- up 36 percent since 1984, according to the U.S. National Center for Health Statistics.
Preterm births, defined as births occurring before the 37th week of pregnancy, are risky for mothers and newborns alike. “For the moms, there are risks in the treatments used to try to halt labor and risks of infection,” says Duke obstetrician Amy Murtha, MD, a specialist in high-risk pregnancies.
For the baby, there are a whole host of concerns that range from the immediate to the lifelong: lung and breathing disorders, problems with vision, and even cerebral palsy are much more common in these babies than in those who go full term.
“And even when the babies turn out OK,” says Murtha, “the costs and stress to families from weeks spent in the NICU can be huge.”
The most common immediate cause for preterm birth is early onset of labor, and the majority of those cases are the result of medical interventions -- situations where the health care provider must treat dangerous conditions in the mother or the baby, and that treatment triggers early labor.
In these situations, says Murtha, there’s sometimes more serious risk to the mother or the baby without intervention than the risks of early delivery itself.
But about 40 percent of cases of early labor are spontaneous, and determining why such preterm labor occurs is a complex puzzle.
“Several different factors may be in play, even in one patient,” says Murtha. “We’re working really hard in the lab to understand the whys behind preterm birth. There’s a lot related to inflammatory response -- you’ve had an infection, you smoke, you’ve had bleeding -- and the consequences of that inflammation,” which scientists believe may harm the tissues in the womb that nourish and protect the fetus.
Researchers are also finding some cases of bacterial infection that has been missed in routine testing during pregnancy. “These bacteria may turn out to be very important, perhaps ultimately something we screen for and treat.”
To help more moms carry their babies to full term, prevention is the key. For the most part, that means moms-to-be doing everything they can to stay healthy before and during their pregnancy.
“Smoking and weight play a role in preterm birth, so there are things mothers can do,” notes Murtha.
But the biggest risk factor of all is prior preterm birth. “The risk of preterm birth is double among these women, and it goes up with each preterm birth that follows.”
For women who have had prior preterm births, a synthetic version of the hormone progesterone called 17P, which is given as a weekly shot starting at 18 weeks, has shown a 35 percent reduction in preterm births.
In 2006, the North Carolina General Assembly funded the 17P Project to educate health care providers and consumers about 17P and provide it free to low-income women.
But Murtha, who serves on the 17P Project’s advisory council, says she balances her counseling to patients about 17P because the long-term consequences of using this drug are not known. In the lab, she and her colleagues are taking a careful look at how the progesterone may play a role in protecting the tissues that surround and nurture a growing fetus.
“It probably protects the cells in these tissues from cell death,” she says, adding, “We don’t have a lot else to offer these women beyond close monitoring, so this treatment option is significant.”
Some babies seem determined to come early despite all efforts to keep them in the womb to term. When preterm birth is inevitable, the focus shifts from prevention to maximizing the baby’s readiness for the world.
“We’ll give steroid injections to promote lung maturity and prevent those respiratory complications,” Murtha says. The steroids are intended to help prevent or minimize other common complications in premature babies, such as bleeding in the brain or intestinal complications.
“We have an incredible obstetrical team here at Duke,” says Ronald Goldberg, MD, who directs the Neonatal ICU. “We do well in large part because the obstetricians give us babies in better shape. What happens up to delivery makes all the difference in terms of the outcome.”
Post-delivery, Goldberg and the rest of the Duke Neonatal Intensive Care Unit (NICU) staff use a variety of tactics to protect fragile preemies and help them thrive. The Duke team is part of the neonatal Research network, which reviews and develops evidence-based, “best practice” standards for the many issues that face premature babies, including:
Better breathing: By adopting a more consistent, standardized approach to getting infants off the respirator quickly, Duke significantly decreased the incidence of chronic lung disease in babies born with respiratory problems. An ongoing study is also showing positive prospects for less-invasive options for keeping the airways open and promoting healthy breathing patterns.
A technique called high-frequency ventilation, which tends to be gentler to the lungs, has also come into practice, thanks in part to safety protocols defined by Duke researchers.
Protecting tender skin: The skin of premature infants is so fragile that attaching monitors could tear it, leading to infections. Duke neonatal nurses developed a skin care team that has succeeded in largely eliminating these skin problems.
Dampening sound: Current studies pointing to the damaging effects of noise on the development of preterm infants are making noise reduction a priority in the NICU.
Involving parents: “We’re now allowing the parents to participate in the medical team’s rounds,” says Goldberg. “They can listen, ask questions, and get instant feedback.”