What the New Study On Preterm Birth Actually Means

A new study that was published last week in the New England Journal of Medicine, and that gained significant media coverage, addresses the sad issue of early preterm birth and the ensuing high levels of infant mortality. However, the findings of the study are being misrepresented — by some groups inadvertently and by others intentionally — so I would like to set the record straight.

For the new data analysis, funded by the National Institutes of Health, outcomes were recorded for approximately 5,000 babies delivered before 27 weeks gestation; this is very early term, as full term begins at 39 weeks. Of the infants delivered after 26 weeks, 80 percent survived. However, of those delivered at 22 weeks, overall only 5 percent survived.

Some media coverage of this data has heralded the survival rates as demonstrating that the “viability age” has been newly established at 22 weeks. But that’s not accurate, because a 5 percent survival rate is very low.

As an obstetrician-gynecologist, I work closely with families who are experiencing preterm birth and who are facing the tragic prospect of losing their newborn or a lifetime of illness. Unfortunately, as a result of some of the media coverage of this data, they may expect better outcomes than what is likely. The sad reality is that even with the best medical care, early preterm birth remains dangerous.

Worse, some critics of reproductive choice might suggest that the findings of this paper point to a downward trend in the “age of viability,” and that continued work in this field is sure to lower it further. Their goal is to limit abortion access through a 20-week ban based on the mistruth that viability is possible at 20 weeks gestation. But that is just not the case.

Here is what the new data actually mean for health care:

Early preterm birth — generally defined at birth before 34 weeks of gestation — can have a variety of causes. That’s why health care providers, including ob-gyns, monitor pregnant women to identify signs of preterm birth and to prevent labor, if possible.

They have made some progress; the Centers for Disease Control and Prevention reports that births before 37 weeks had dropped to 11.38 percent in 2013 from 12.8 percent in 2006; this decrease meant more families avoiding the poor outcomes commonly associated with preterm birth.

For many premature infants, those outcomes are significant. Although risks are greatest for infants born before 34 weeks of gestation, those that are born after 34 weeks of gestation but before 37 weeks of gestation – still preterm, but not early preterm – are still more likely to experience delivery complications, long-term impairment, and early death than those born later in pregnancy.

What’s more, infants born prematurely have increased risks of mortality and morbidity throughout childhood, especially during the first year of life.

Without a doubt, longer gestation allows fetuses a better chance at a healthy infancy. That’s why it’s not surprising that we have sought to identify the point in gestation at which fetuses can survive outside of the uterus.

But the challenge is that gestation is a gradual process, with no set moment at which a fetus would be viable upon delivery. There is also variability in fetal development, which means that viability for one fetus at a particular stage does mean viability for another at that same stage. Without a doubt, the earlier in pregnancy a baby is delivered, the more it will struggle to survive, even with the best medical care. That is what last week’s data demonstrates.

While mischaracterizing or misunderstanding data can be troublesome, misappropriating data to serve a political interest is just plain wrong. Studies like this week’s are meant to further our understanding of the medical universe, and our ability to tailor our care so that our patients benefit. Let us add this data to our arsenal of medical understanding and continue to work toward caring for those who need it.

Hal C. Lawrence, MD, is the Executive Vice President and CEO of the American College of Obstetricians and Gynecologists.