Even extremely preterm infants have a high likelihood of survival today in settings with active perinatal care, a large Swedish study has found.
... Among 707 infants born before gestational week 27, some 91% were admitted to neonatal intensive care units and 70% survived to one year ...
The overall perinatal mortality was 45%, and ranged from 24% among infants at 26 weeks gestation to 93% at 22 weeks ...
Preterm births have been increasing worldwide, and advances in perinatal medicine have been saving some of the most immature infants, but uncertainties remain about survival rates, developmental difficulties, and high costs.
... Of 305,318 total infants born, 1,011 arrived before week 27, for an incidence of extreme prematurity of 3.3 per 1,000 infants.
A total of 707 babies (70%) were live born, while 304 (30%) were stillborn.
There were 102 multiple births (11%).
... 7% of the pregnancies resulted from in vitro fertilization.
Clinical complications such as preeclampsia or antepartum hemorrhage occurred in 36% of the pregnancies.
A total of 210 live-born babies (30%) died before one year, including 152 (22%) who died during the first week of life. Of those who died, 8% died in the delivery room, and 5% died between days 7 and 27, the investigators found.
... an increased risk of death was associated with the infant being small for gestational age (OR 1.69, 95% CI 1.12 to 2.58, P=0.04) or a multiple birth (OR 1.70, 95% CI 1.04 to 2.77, P=0.01).
Among the infants who survived for at least 24 hours and were born at 22 weeks, the chance of one-year survival was lower than for those born at 23 or 24 weeks (OR 0.22, 95% CI 0.06 to 0.71, P=0.01).
Those infants, in turn, had a lower survival rate than those born at 25 or 26 weeks (OR 0.50, 95% CI 0.32 to 0.78, P=0.002), according to the investigators.
Overall survival at one year was: 10% for infants born at 22 weeks 53% for those born at 23 weeks 67% for those born at 24 weeks 82% for those born at 25 weeks 85% for those born at 26 weeks
... factors the investigators identified as being associated with a lower risk of death were:
Antenatal tocolytic treatment (OR 0.60 ... ) Antenatal corticosteroid treatment (OR 0.41 ... ) Surfactant treatment within two hours after birth (OR 0.48 ... ) Birth at a level III hospital (OR 0.78 ...)
Cesarean delivery, however, was not associated with a lower risk of death (OR 0.98 ... ).
... The findings of the study highlight the improvements in survival among extremely premature babies since a previous cohort of 931 Swedish babies born between 1990 and 1992 at less than 1,000 grams was studied.
... Aside from a more interventional approach, egalitarian Swedish health policies also may have helped in the increased rates of survival, with adherence to antenatal care programs being nearly universal.