Eunice Kennedy Shriver National Institute of Child Health and Human Development SALT LAKE CTY, UT, United States
Objective: Neonatal survival probabilities are important in shared decision-making considerations for peri-viable deliveries. The NICHD NRN Survival Probability Estimator has been used for counseling and treatment decisions but considers very few prenatally available data. We asked whether: 1) using an ultrasonographic estimated fetal weight (EFW) within one week of delivery rather than birthweight resulted in significantly different predicted survival probabilities, or 2) predicted probabilities were different based on the indication for delivery.
Study Design: Secondary analysis of an observational cohort of deliveries from 16 0/7 through 34 6/7 weeks from January-August 2019 at 34 U.S. hospitals. Patients were included if they had an ultrasonographic estimated fetal weight (EFW) within one week of delivery and a live birth of a non-anomalous infant from 22 0/7 through 25 6/7 weeks. The primary outcome was neonatal survival as estimated from the NRN Estimator. The Estimator uses birthweight, newborn sex, plurality, and antepartum steroid exposure to generate the survival probability. We assessed whether predicted survival was significantly altered after substituting birthweight for EFW, and after partitioning of the cohort by whether 1) PPROM (as primary reason for delivery admission), 2) hypertensive disorders of pregnancy (HDP), or 3) spontaneous premature birth (SPTB) had occurred.
Results: 275 neonates met inclusion criteria. At each week of gestational age the median survival estimate using EFW was not statistically different from that estimated using birthweight. However, the predicted survival was dependent upon whether the selected obstetric complications had occurred. Specifically, birth after SPTB or PPROM identified a group of neonates with a higher probability of predicted survival after 23 weeks.
Conclusion: EFW instead of birthweight does not alter NRN Estimator survival probabilities. The findings that predicted survival probabilities varied by indication for delivery warrants further assessment.
