82 - Is the Baby Actually 22 Weeks? Gestational Age Dating Method, Management, and Outcome of Extremely Preterm Infants, 2018-2020

Poster Number: 82
Publication Number: 82.437

Matthew Rysavy, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States; Scott A. McDonald, RTI International, RALEIGH, NC, United States; Suneet P. Chauhan, McGovern Medical School at UTHouston, Houston, TX, United States; BRIAN M. MERCER, CWRU - The MetroHealth System, Cleveland, OH, United States; Maria del Mar Romero Lopez, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States; Lindsay F. Holzapfel, University of Texas, Houston Health Science Center, Houston, TX, United States; Noelle Younge, Duke University School of Medicine, Durham, NC, United States; Ravi M. Patel, Emory University and Children's Healthcare of Atlanta, Atlanta, GA, United States; Abhik Das, RTI International, North Potomac, MD, United States; Jon Tyson, UT Health, houston, TX, United States; Edward F. Bell, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA, United States

Background: Gestational age (GA)-specific data from large research networks are used to benchmark management and outcomes, provide prognostic estimates, and study intervention safety and efficacy. Little is known about methods of GA determination used for these purposes.

Objective: To determine: 1) methods used for GA determination in the NICHD Neonatal Research Network (NRN); and 2) whether these methods are associated with management and survival.

Design/Methods: Retrospective cohort study of data collected prospectively at 15 U.S. NRN centers. Study included all inborn infants born alive without birth defects at 22 0/7 -28 6/7 weeks’ GA between 1/1/2018 and 12/31/2020. Based on the recommendation by the American College of Obstetricians and Gynecologists and others that ultrasound measurements obtained < 14 weeks are “the most accurate method to establish or confirm gestational age,” infants were categorized as having optimal or suboptimal dating based on whether first obstetric ultrasound was performed at < 14 weeks. Infant characteristics, survival to discharge, and active postnatal treatment were compared by GA dating method and GA at birth. For infants born at 22 0/7- 25 6/7 weeks, actual survival was compared against predicted survival based on the NICHD Extremely Preterm Birth Outcome Tool (nichd.gov).

Results: Of 5233 eligible infants, 4791 were included in the analysis (Figure 1). Of these, 3477 (72.5%) had a first ultrasound at < 14 weeks, 1124 (23.5%) had a first ultrasound at ≥14 weeks, and 190 (4.0%) had obstetric dating without confirmatory ultrasound or postnatal dating. Median time of first ultrasound dating was 10 (IQR 7-14) weeks. There was no association of dating method and GA at birth, although several other characteristics differed by dating method (Table 1). Optimally dated infants had higher rates of survival at 22 weeks and lower rates at 23 weeks, with no differences at other gestational ages (Table 2). There were no differences in active treatment rate by dating method. Dating method did not affect survival prediction with the NICHD Extremely Preterm Birth Outcome Tool; however, observed survival was uniformly higher than predicted by the tool, which was developed using data from 2006-2012.Conclusion(s): In NRN centers, more than two-thirds of extremely preterm infants had reliably obtained first-trimester ultrasounds to confirm the due date. GA dating reliability was not associated with active treatment, but was associated with survival at 22 and 23 weeks’ gestation. Future studies should consider GA dating reliability in reporting infant outcomes.
Figure 1. Patient inclusion flowchart
Table 1. Characteristics by gestational age dating method