Medicine has made tremendous strides since the 1980s on the survival of extremely premature babies, as illustrated by several medical studies published this week related to the United States and Sweden.
Until the 1980s, medicine considered the minimum gestational age for viability to be 28 weeks, from 40 to normal gestation (babies are considered premature before 37 weeks). At 28 weeks, babies weigh only about 1,000 grams.
This limit has steadily declined since then and babies survive at 24, 23 and up to 22 weeks, when they weigh a pound and even less. A Japanese baby jumped to headlines in February for weighing 268 grams at birth after 24 weeks of gestation, and managed to overcome five months of hospitalization and get out of there healthy.
"I have been following this question for 40 years and have seen the viability threshold come back a week every 10 years in my hospital," Edward Bell, a neonatal physician and professor of pediatrics at the University of Iowa hospital, told AFP. U.S.
Sweden holds the world's survival record: 77% of children born between 22 and 26 weeks in 2014-2016 survived the first year, a study published on Tuesday in the Journal of the American Medical Association, Jama. Survival in 2004-2007 was 70%.
Sweden standardized procedures and systematized the resuscitation of preterm infants: immediate intubation, drug administration and rapid transfer to a neonatal intensive care unit. Currently, 88% of premature births in the northern European country are performed in hospitals equipped with this unit.
"Previously, in front of a baby born at 22 or 23 weeks, a doctor could say it was not worth doing anything," said Mikael Norman, MD, a co-author of the study.
For the youngest of 22 weeks, survival went from 3.6% to 20% in a decade. Among those born at 26 weeks, eight out of ten survive.
– United States overdue –
Since the 1990s, three major breakthroughs have been the invention of artificial "surfactants," which replace a substance that very premature babies do not yet produce in their lungs and helps them breathe; injection of steroids into the mother just before delivery, which causes the fetus' lungs to mature for a week in a day; and improvements in respiratory devices.
These techniques are widely available in developed countries, but this does not prevent significant disparities from one country to another and even from one hospital to another.
In France, the United Kingdom and the United States, approximately half of very premature babies (less than 26 or 27 weeks gestation) survived, according to studies dating back a few years.
But unlike Sweden, in the United States, the health system is very uneven.
Another study published in Jama showed that geographic segregation between blacks and whites was replicated in hospitals: black preterm babies are born in poor quality centers.
However, survival is advancing, even for babies weighing less than 400 grams, very rare cases that were the subject of another study in Jama released on Monday.
13% of infants less than 400 grams and born between 22 and 26 weeks in 21 hospitals in the United States from 2008 to 2016 survived. One of them weighed only 330 grams.
But at this age, the risk of complications is high: three quarters had developmental delays in two years.
"It shows that survival is possible," says Edward Bell, one of the study's authors. "It can not be said openly that these babies should always be resurrected, but parents should receive this information and give their opinion to decide on their resuscitation."