Delaying Delivery 24 to 96 Hours Improves Survival for 23-Week Infants

October 15, 2012

To better understand the differences in 23-week survival rates and outcomes in infants born “early” (23 weeks 0/7 to 3/7) and “late” (23 weeks 4/7 to 6/7), researchers analyzed the records of 126 consecutive liveborn 23-week infants classified as either early or late by gestational age at birth.

The percentage of infants delivered at 23 weeks is low, but the percentage of perinatal death of these infants is high. Twenty-three weeks’ gestation represents what is generally considered at the limits of viability. Over the years, as new therapies and treatments have been developed, significant improvement in the rates of neonatal morbidity and mortality has been noted for preterm infants born at or after 24 weeks’ gestation. For infants born at 23 weeks, however, the evidence showing similar improvements is quite limited and inconclusive.

To better understand the differences in 23-week survival rates and outcomes in infants born “early” (23 weeks 0/7 to 3/7) and “late” (23 weeks 4/7 to 6/7), researchers from Saint Louis University School of Medicine in St Louis, Missouri, analyzed the records of 126 consecutive liveborn 23-week infants classified as either early (n=72) or late (n=54) by gestational age at birth.1 In some cases, an advance directive to not resuscitate had been given, and these infants-12 of whom were initially in the early group and 2 in the late group-were assigned to a group called comfort care.

The study findings showed that infants in the late group were significantly more likely to survive than infants in the early group (56% vs 25%, respectively; P < .001)). The infants who survived had “almost universal morbidity,” according to the study authors. Significant predictors of survival were late 23-week gestational age and birth weight. The average birth weight for the early group was 546.92 grams, and that for the late group was 595.98 grams.

Overall, 66 of the 126 infants received antenatal corticosteroids, and 102 of 126 infants received surfactant. The late group was more likely than the early group to have been administered antenatal corticosteroids, and a subanalysis showed that the survival rate was higher in the corticosteroid group than in the no-corticosteroid group (46% vs 30%, respectively) regardless of when delivery occurred (early vs late). Whether the babies were born in the study-affiliated tertiary care center (inborn) or transferred to the study facility from another hospital (outborn) had no significant effect on survival (P = .183).

The authors suggest that these findings may warrant prolonging a pregnancy 24 to 96 hours so that delivery can occur at or after 23 weeks and 4 days. However, the authors also support comfort care. “Comfort care counseling remains a reasonable and standard accepted option for patients who are well informed about the morbidity and mortality of a 23-week infant,” write the study authors.

Pertinent Points:
- Infants born at or after 23 weeks and 4 days’ gestation are significantly more likely than infants born earlier to survive, but the morbidity rate in the survivors is nearly 100%.
- In the past 10 years, there has been no improvement in survival rates of infants born at 23 weeks’ gestation.
- Additional research is needed to identify which interventions provide the greatest benefits in terms of morbidity and mortality in 23-week infants.

References:

1. Nguyen TP, Amon E, Al-Hosni M, et al. “Early” versus “late” 23-week infant outcomes. Am J Obstet Gynecol. 2012;207:e1-e6.