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Neonatal Outcomes of Elective Early Term Births after Demonstrated Fetal Lung Maturity


Tita, Alan T. N.; Jablonski, Kathleen A.; Bailit, Jennifer L.; Grobman, William A.; Wapner, Ronald J.; Reddy, Uma M.; Varner, Michael W.; Thorp, John M., Jr.; Leveno, Kenneth J.; & Caritis, Steve N., et al. (2018). Neonatal Outcomes of Elective Early Term Births after Demonstrated Fetal Lung Maturity. American Journal of Obstetrics & Gynecology, 219(3), 296.e1-8. PMCID: PMC6143365


BACKGROUND: Studies of early term birth after demonstrated fetal lung maturity show that respiratory and other outcomes are worse with early term birth (37(0)-38(6)) even after demonstrated fetal lung maturity when compared with full term birth (39(0)-40(6)). However these studies included medically indicated births and are therefore potentially limited by confounding by the indication for delivery. Thus the increase in adverse outcomes might be due to the indication for early term birth rather than the early term birth itself.
OBJECTIVE: We examined the prevalence and risks of adverse neonatal outcomes associated with early-term birth after confirmed fetal lung maturity as compared with full term birth in the absence of indications for early delivery.
STUDY DESIGN: Secondary analysis of an observational study of births to 115,502 women in 25 hospitals in the United States from 2008-11. Singleton non-anomalous births at 37-40 weeks with no identifiable indication for delivery were included; early term births after positive fetal lung maturity testing were compared with full-term births. The primary outcome was a composite of death, ventilator for >/=2 days, CPAP, proven sepsis, pneumonia or meningitis, treated hypoglycemia, hyperbilirubinemia (phototherapy) and 5 min Apgar <7. Logistic regression and propensity score matching (both 1:1 and 1:2) were used.
RESULTS: 48,137 births met inclusion criteria; the prevalence of fetal lung maturity testing in the absence of medical or obstetric indications for early delivery was 0.52% (n=249). There were 180 (0.37%) early-term births after confirmed pulmonary maturity and 47,957 full-term births. Women in the former group were more likely to be non-Hispanic White, smoke, have received antenatal steroids, have induction and have a cesarean. Risks of the composite (16.1% vs. 5.4%; adjusted odds ratio 3.2; 95% CI 2.1-4.8 from logistic regression) were more frequent with elective early term birth. Propensity scores matching confirmed the increased primary composite in elective early-term births: adjusted odds ratios 4.3 (1.8-10.5) for 1:1 and 3.5 (1.8-6.5) for 1:2 matching. Among components of the primary outcome, CPAP use and hyperbilirubinemia requiring phototherapy were significantly increased. Transient tachypnea of the newborn, neonatal intensive care unit admission and prolonged neonatal intensive care unit stay (>2 days) were also increased with early term birth.
CONCLUSIONS: Even with confirmed pulmonary maturity, early term birth in the absence of medical or obstetric indications is associated with worse neonatal respiratory and hepatic outcomes compared with full-term birth, suggesting relative immaturity of these organ systems in early term births.


Reference Type

Journal Article

Year Published


Journal Title

American Journal of Obstetrics & Gynecology


Tita, Alan T. N.
Jablonski, Kathleen A.
Bailit, Jennifer L.
Grobman, William A.
Wapner, Ronald J.
Reddy, Uma M.
Varner, Michael W.
Thorp, John M., Jr.
Leveno, Kenneth J.
Caritis, Steve N.
Iams, Jay D.
Saade, George R.
Sorokin, Yoram
Rouse, Dwight J.
Blackwell, Sean C.
Tolosa, Jorge E., for the
Eunice Kennedy Shriver
National Institute of Child Health and Human Development (NICHD) Maternal-Fetal Medicine Units (MFMU) Network