If you saw Erinn and Rowan Cuddy today, you would never guess they had a rough start in life. The 9-month-old twins, who live in Redwood City, California, are hardy, healthy, and rambunctious. They're starting to talk, and they obviously have big plans for the future.

Nine months ago, things didn't seem nearly as secure: Erinn and Rowan were born at just 33 weeks gestation (about six weeks ahead of schedule). Erinn didn't have any major complications, but Rowan needed a respirator to help him breathe. "The saddest thing was when he started to cry," says his mom, Sabrina Cuddy, the online community manager for Consumer Health Interactive and a certified birthing instructor. "Because he was on a respirator, no sound came out."

Such heartbreaking scenes have become commonplace at neonatal intensive care units across the country. According to the March of Dimes, the rate of premature births has climbed 27 percent since 1981. About 508,356 American babies born in 2004 -- or roughly one out of eight -- were premature.

Premature birth is now the leading cause of death and long-term disability among newborns. As reported by the March of Dimes, the average cost of a premature baby's hospital stay is about $77,000. Some babies never recover, but modern medicine gives even the tiniest preemies a fighting chance. Most will eventually go home with their parents, and a good number will have normal, healthy lives. But doctors know this success is clouded by one major failure: Despite their best efforts, they haven't been able to prevent premature births from happening in the first place.

Why are premature births on the rise, and what can be done to reverse the trend? Siobhan Dolan, M.D., assistant medical director for the March of Dimes, has a short, unsettling answer: Nobody really knows. The factors that can lead to premature birth are extremely complex, she says. One thing is clear: If doctors ever hope to stop this epidemic, they'll have to understand the forces behind it.

A boom in multiple births is clearly one of the biggest culprits, Dolan says. Twins, triplets, quadruplets, and so on are much more likely than single babies to be born before their time. Multiple births are on the rise because more and more women in their late 30s or early 40s are having babies, and women over 35 are more likely than younger women to conceive multiples. Sabrina Cuddy, for example, was 36 when she had Erinn and Rowan. Older women are also much more likely to use fertility treatments, which often lead to a multiple pregnancy. (Cuddy conceived the old-fashioned way.)

Also accompanying the rise in premature births are an increase in "silent" bacterial and viral infections, obesity rates, and the abuse of alcohol and other drugs, according to the February 3, 2003 issue of Contemporary Ob/Gyn. (It's unclear, however, whether it's the drug use or other social and economic factors that are contributing to premature birth, according to the journal.) The authors also point to new findings that associate maternal stress with preterm labor, "especially if it occurs early in pregnancy and is a type over which the woman has little control, such as the stress associated with catastrophic events, domestic violence, and racism."

Although almost half of all premature births have no clear cause, according to the March of Dimes, other risk factors are well-known. For pregnant women, smoking cigarettes is a major preventable causes of preterm birth. Genital tract infection like bacterial vaginosis may result in preterm delivery. And lack of prenatal medical care also contributes to many premature births, especially among poor women, Dolan says. Poor and minority women are less likely than affluent white women to receive prenatal care, and they are also more likely to give birth prematurely. "Prenatal care is absolutely essential for all women," she says.

The good news is that more women of all races and classes are getting prenatal care than ever before. (Sabrina Cuddy, for one, saw her doctor early and often.) Unfortunately, this positive trend hasn't made a dent in the rise in premature births, so other factors appear to be erasing the potential gains of prenatal care. Perhaps, Dolan says, the care is just coming too late.

In this age of sky-high health costs, a growing number of uninsured women can't afford routine doctor visits, Dolan says. Medicaid often helps cover prenatal care, but not "preconception" care. As a result, too many women fail to get the treatments that could prove crucial to the success of future pregnancies. "They may have hypertension and diabetes, but they can't access medical care until they are pregnant," she says. Women who rarely see a doctor are also less likely to make baby-friendly lifestyle changes such as quitting smoking, taking folic acid supplements, and maintaining a healthy body weight, she says. (For more information on lifestyle and premature births, see our primer on preventing premature births.)

As recent studies have suggested, increasing rates of obesity may have contributed to the epidemic of premature births. "Weight before pregnancy matters much more than people realize," says Dr. Richard J. Deckelbaum, a professor of nutrition at Columbia University, in a March of Dimes press release. "For the moms, there are serious complications [from being extremely overweight] such as gestational diabetes, dangerously high blood pressure, and hospitalization; for the babies, it can cause prematurity, serious birth defects, and other severe problems."

Other researchers put the blame on stress. Pregnant women who are under considerable stress produce higher levels of a hormone linked to premature labor, according to a 1999 study reported in the Journal of Obstetrics and Gynecology.

For now, it's largely just guesswork, Dolan says. In the end, nobody knows why premature births are increasingly common, or how to reverse this trend. The March of Dimes is trying to take a major step in the right direction with a $75 million campaign to improve medical care for pregnant women and increase awareness of prematurity.

Will the campaign work? Again, nobody knows. The only certainty is that a woman should do everything she can to have a successful pregnancy, Dolan says. That means getting medical care, staying away from cigarettes, eating well, and generally taking care of herself. Women at risk for preterm birth or labor should also be screened for common vaginal infections and treated, if necessary. With any luck, that will mean one less baby starting life in an incubator.

-- Chris Woolston, MS, is a health and medical writer with a master's degree in biology. He is a contributing editor at Consumer Health Interactive and a former staff writer at Hippocrates, a national magazine for physicians. He has also covered science issues for Time Inc. Health, WebMD, Health, and the Chronicle of Higher Education.

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First published July 9, 2003
Last updated January 17, 2007
Copyright © 2003 Consumer Health Interactive