For premature babies born at the edge of viability, the chance of survival without serious health problems has gotten slightly better, at least at the nation's top neonatal care centers — a small change with potential implications for the bitter abortion debate in Pennsylvania and other states.
Researchers from the 11 centers analyzed the records of more than 4,200 babies born at 22 to 24 weeks of pregnancy between 2000 and 2011. While the grim picture at 22 weeks did not change — 96 percent of newborns died — the outlook for the rest of the "periviable" infants improved over the 12-year period.
In the final four years of the study, more than a third of babies born at 23 and 24 weeks survived. By the time those survivors were toddlers, about 20 percent — one in five — had no developmental impairments.
The findings, published Wednesday in the New England Journal of Medicine, are sure to add to the debate about whether to change the threshold of fetal viability — the point at which the fetus can survive independently outside the womb — from the current medical consensus of 24 weeks.
For professional medical groups, lowering that standard has implications for when and how intensively to treat newborns that average just over a pound. For foes of abortion, a change could help further restrict the procedure, because the Supreme Court has said states can ban abortion of viable fetuses except when the mother's health is at stake.
Even though late-term abortion is uncommon and often involves devastating fetal abnormalities, 19 states have enacted laws banning abortion at 20 weeks.
Pennsylvania's Senate passed such a bill this month. Mayor Kenney and Gov. Wolf held a joint news conference decrying the measure on Wednesday, and Wolf said he would veto it.
"A lot of medical societies are struggling with this, what to do about babies born at 22 and 23 weeks," said Prakesh S. Shah, a University of Toronto neonatologist and health policy researcher who wrote an editorial accompanying the new study. "The majority would say 22 weeks is the age of nonviability."
Shah's editorial cited recent studies from developed countries that also show the drastic difference a week or so can make. Rates of death or developmental impairments were over 94 percent for infants born at 22 weeks, 80 to 90 percent at 23 weeks, and 51 to 72 percent at 24 weeks.
Last summer, the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine updated its guidance on periviable birth. While resuscitation of a newborn is "recommended" at 24 weeks, it is something to "consider" at 22 and 23 weeks, and "not recommended" at earlier gestational ages, the group said.
Infants born long before completing a full 40-week gestation pose huge biological challenges; most survivors have lifelong disabilities such as cerebral palsy, hearing and vision loss, mental impairment, and movement problems.
"All of the organ systems are immature," said Duke University neonatologist Noelle Younge, lead author of the new study. "They're at risk for brain injury because of bleeding in the brain. The lungs are very immature as well. They just haven't developed enough to sustain life."
Vincenzo Berghella, director of maternal-fetal medicine at Thomas Jefferson University, who was not part of the new study, said: "It's true that we ... can keep babies alive earlier and they have slightly better outcomes. But the average IQ of babies born at 24 weeks is 70."
Still, medical technology to protect and support immature organs has advanced. For example, steroids and gentler ventilation reduces preemies' respiratory distress, which improves circulation, which in turn reduces the risk of bleeding.
"The culture of neonatal intensive care units has really changed in the past decade," said senior author C. Michael Cotten, a Duke neonatologist.
Authors of the study caution that their results may be better than the norm. The 4,200 babies were born in academic medical centers — including the University of Pennsylvania/Children's Hospital of Philadelphia — that are part of a federally funded neonatal research network. Those babies represent only 5 percent of periviable infants born in the United States.
And even though the study is one of the largest to date, the numbers in each category are small enough that the researchers say the improvements could "reflect random variation alone."
Out of all the periviable infants — including the 22-week-olds, who did not have improved outcomes — the total number who survived without neurodevelopmental impairment rose from 217 (16 percent) in 2000-03 to 276 (20 percent) in 2008-11.
The number who survived with impairments increased, but just barely — from 207 in the initial years to 211 at the end.
Total deaths decreased from 967 (70 percent) at the outset to 861 (64 percent) at the end.