Survival and Impairment of Extremely Premature Infants: A Meta-analysis.

CONTEXT

Survival of infants born at the limit of viability varies between high-income countries.

OBJECTIVE

To summarize the prognosis of survival and risk of impairment for infants born at 22 + 0/7 weeks' to 27 + 6/7 weeks' gestational age (GA) in high-income countries.

DATA SOURCES

We searched 9 databases for cohort studies published between 2000 and 2017 in which researchers reported on survival or neurodevelopmental outcomes.

STUDY SELECTION

GA was based on ultrasound results, the last menstrual period, or a combination of both, and neurodevelopmental outcomes were measured by using the Bayley Scales of Infant Development II or III at 18 to 36 months of age.

DATA EXTRACTION

Two reviewers independently extracted data and assessed the risk of bias and quality of evidence.

RESULTS

Sixty-five studies were included. Mean survival rates increased from near 0% of all births, 7.3% of live births, and 24.1% of infants admitted to intensive care at 22 weeks' GA to 82.1%, 90.1%, and 90.2% at 27 weeks' GA, respectively. For the survivors, the rates of severe impairment decreased from 36.3% to 19.1% for 22 to 24 weeks' GA and from 14.0% to 4.2% for 25 to 27 weeks' GA. The mean chance of survival without impairment for infants born alive increased from 1.2% to 9.3% for 22 to 24 weeks' GA and from 40.6% to 64.2% for 25 to 27 weeks' GA.

LIMITATIONS

The confidence in these estimates ranged from high to very low.

CONCLUSIONS

Survival without impairment was substantially lower for children born at <25 weeks' GA than for those born later.