More 'Extreme' Preemies Surviving
TUESDAY, June 2 -- Advances in the care of extremely premature infants mean that about 70 percent of these tiny newborns now survive their first year of life, Swedish researchers report.
The number of preterm births is increasing worldwide, and advances in perinatal medicine have increased survival. That means that neonatal intensive care can now be lifesaving even for the most premature infants -- those born between 22 and 26 weeks of gestation.
The news is important, the researchers said, because if parents and doctors believe a preemie's chances for survival are already slim, less aggressive care might be extended.
But the new results suggest that the evaluation of "extremely preterm babies should be done individually, considering both the survival chances and the morbidity risks," said Dr. Karel Marsal, a professor of obstetrics and gynecology at Lund University and the lead researcher.
"The survival rates of extremely preterm infants are high, even at the borders of viability," he noted.
The report is published in the June 3 issue of the Journal of the American Medical Association.
For the study, Marsal's group collected data on more than 305,000 infants born in Sweden from 2004 to 2007. Among these infants, 1,011 were born extremely preterm (before 27 weeks), including 707 born alive and 304 stillborn.
After one year, 70 percent of the 707 children were still alive, with dramatic increases in survival for each additional week of gestation. For babies born at 22 weeks, one-year survival was 9.8 percent; at 23 weeks it was 53 percent; at 24 weeks, survival was 67 percent; at 25 weeks it was 82 percent; and at 26 weeks, one-year survival reached 85 percent.
Among the surviving infants, 45 percent had no severe neonatal illness at 1 year old.
The overall perinatal death rate was 45 percent, ranging from 93 percent at 22 gestational weeks to 24 percent at 26 weeks, the study found. Among live births, 22 percent of the infants died within six days of delivery, including 8.2 percent who died in the delivery room and 5 percent died from seven to 27 days after birth.
Altogether, 30 percent of the infants who were born alive died before the age of 1 year. The number of stillbirths, delivery room deaths, neonatal deaths and infant deaths decreased with gestational age. For infants surviving 28 days, there was no significant association between gestational age at birth and one-year survival, Marsal's team found.
Treatment with tocolytics, which are drugs that delay or stop labor, corticosteroids or both appeared to help lower the odds of death. So did treatment soon after birth with surfactant -- a fluid produced shortly before birth that prevents the lungs from filling with water. Birth at an "advanced care" hospital was also associated with a lower risk of infants dying, the Swedish team found.
"We believe that the good Swedish results are due to the excellent collaboration between obstetricians and neonatologists, a high degree of centralization of very preterm deliveries to tertiary level perinatal centers, and proactive perinatal management," Marsal said.
Dr. F. Sessions Cole, director of newborn medicine and head of the neonatal intensive care unit at St. Louis Children's Hospital, believes that more needs to be done to prevent premature delivery in the first place, however.
"Gestational age at the time of delivery continues to be an important predictor of a live birth, survival until discharge from the neonatal intensive care unit, and survival until one year of age," he said.
Because the study was executed as an observational study, it did not look into ways to prevent preterm birth or improve neonatal outcomes, Cole said.
Parents need "personalized prognostic tools, both to inform decision-making about neonatal outcomes and to prevent extremely preterm birth," he said.
The U.S. National Institute of Child Health and Human Development has more on preterm labor and birth.
Posted: June 2009
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