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Perinatal factors influencing survival at twenty-four weeks' gestation
R K Silver1, S N MacGregor, E E Farrell
1Evanston Hospital, IL 60201.
Insights
Survival at 24 weeks gestation depends on gestational age and intensive care. Aggressive intrapartum and neonatal interventions, including surfactant, improved outcomes for these extremely premature infants.
Area of Science:
- Perinatology
- Neonatology
- Obstetrics
Background:
- Infant survival rates at 24 weeks gestation are critically low.
- The introduction of exogenous surfactant aimed to improve outcomes for extremely premature infants.
Purpose of the Study:
- To identify obstetric and neonatal factors influencing survival in infants born at 24 weeks gestation.
- To analyze the impact of intrapartum care and neonatal support on perinatal outcomes.
Main Methods:
- Retrospective review of maternal and neonatal records for infants born between 24 weeks 0 days and 24 weeks 6 days gestation (1987-1989).
- Data abstraction focused on objective risk factors for survival.
- Statistical analysis, including univariate comparisons and logistic regression, was employed.
Main Results:
- Of 52 infants born at 24 weeks gestation, 17 (33%) survived.
- Survivors received more aggressive intrapartum care (fetal monitoring, maternal oxygen, position changes) and neonatal support (resuscitation, surfactant administration).
- Gestational age at delivery was the strongest predictor of survival; respiratory insufficiency was the primary cause of death.
Conclusions:
- Gestational age is the primary determinant of perinatal outcome at 24 weeks gestation.
- Intrapartum care intensity and neonatal support significantly influence survival rates.
- Clinical judgment regarding survivability may also play a role in outcomes.
Objective:
Our objective was to identify those obstetric and neonatal factors associated with survival in infants delivered at 24 weeks' gestation.
Study Design:
The obstetric and pediatric data bases from the two hospitals in our perinatal center were examined to ascertain all infants delivered between 1987 and 1989 whose gestational age was 24 weeks to 24 weeks 6 days. This time interval was chosen to coincide with the introduction of prophylactic exogenous surfactant. Data were abstracted from the maternal antepartum and intrapartum records and the neonatal records, with specific attention to objective risk factors related to survival.
Results:
Forty-five pregnant patients were identified and delivered of 52 infants. Seventeen newborn infants survived (33%). Univariate comparisons between survivors and nonsurvivors revealed more aggressive intrapartum care in the former cohort as represented by the frequencies of internal fetal heart rate monitoring (p = 0.005), maternal oxygen therpay (p = 0.003), and maternal position change to remediate decelerations (p = 0.001). Planned exclusion of cesarean delivery was more common in those pregnancies that ended in fetal or neonatal death (29/35 vs 7/17; p = 0.006). Although a greater proportion of infants delivered by cesarean section survived (6/11 vs 11/41), this difference was not significant (p = 0.17). With the use of logistic regression, the best predictor of survival was gestational age at delivery. Neonatal care was more aggressive among survivors, as measured by the relative frequencies of resuscitation and surfactant administration. Respiratory distress syndrome was either absent (n = 6) or mild (n = 6) in a majority of the survivors, and respiratory insufficiency was the major cause of neonatal death.
Conclusion:
Perinatal outcome at 24 weeks' gestation appears most dependent on gestational age at delivery. The intensity of intrapartum care and neonatal support, as well as clinical biases regarding survivability, may also influence outcome.