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Survival and Impairment of Extremely Premature Infants: A Meta-analysis
Hilde Tinderholt Myrhaug1, Kjetil Gundro Brurberg2, Laila Hov3
1Norwegian Institute of Public Health, Oslo, Norway; himy@fhi.no.
Insights
Infants born at the limit of viability show improved survival and reduced impairment rates with increasing gestational age (GA). Survival without impairment is significantly lower for premature infants born before 25 weeks GA.
Area of Science:
- Neonatalogy
- Perinatology
- Developmental Pediatrics
Background:
- Infant survival rates at the threshold of viability differ across high-income nations.
- Understanding prognosis is crucial for clinical decision-making and parental counseling.
Purpose of the Study:
- To synthesize survival and impairment risks for infants born between 22 and 27 weeks' gestational age (GA) in high-income countries.
- To provide evidence-based data on outcomes for extremely preterm infants.
Main Methods:
- A systematic review of 65 cohort studies published between 2000 and 2017 was conducted.
- Studies reporting survival or neurodevelopmental outcomes were included.
- Data extraction and quality assessment were performed by two independent reviewers.
Main Results:
- Survival rates at 27 weeks' GA reached over 80% for live births and intensive care admissions, compared to near 0% at 22 weeks' GA.
- Severe impairment rates in survivors decreased from 36.3% (22-24 weeks GA) to 4.2% (25-27 weeks GA).
- Survival without impairment increased from 1.2% at 22-24 weeks GA to 64.2% at 25-27 weeks GA.
Conclusions:
- Survival without impairment is substantially lower for infants born before 25 weeks' GA.
- Gestational age is a critical determinant of both survival and neurodevelopmental outcomes in extremely preterm infants.
- Evidence quality varied, necessitating cautious interpretation of estimates.
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.
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