Diagnostic Accuracy of Neonatal Assessment for Gestational Age Determination: A Systematic Review

CONTEXT: An estimated 15 million neonates are born preterm annually. However, in low- and middle-income countries, the dating of pregnancy is frequently unreliable or unknown. OBJECTIVE: To conduct a systematic literature review and meta-analysis to determine the diagnostic accuracy of neonatal assessments to estimate gestational age (GA). DATA SOURCES: PubMed, Embase, Cochrane, Web of Science, POPLINE, and World Health Organization library databases. STUDY SELECTION: Studies of live-born infants in which researchers compared neonatal signs or assessments for GA estimation with a reference standard. DATA EXTRACTION: Two independent reviewers extracted data on study population, design, bias, reference standard, test methods, accuracy, agreement, validity, correlation, and interrater reliability. RESULTS: Four thousand nine hundred and fifty-six studies were screened and 78 included. We identified 18 newborn assessments for GA estimation (ranging 4 to 23 signs). Compared with ultrasound, the Dubowitz score dated 95% of pregnancies within 2.6 weeks (n = 7 studies), while the Ballard score overestimated GA (0.4 weeks) and dated pregnancies within 3.8 weeks (n = 9). Compared with last menstrual period, the Dubowitz score dated 95% of pregnancies within +/- 2.9 weeks (n = 6 studies) and the Ballard score, +/- 4.2 weeks (n = 5). Assessments with fewer signs tended to be less accurate. A few studies showed a tendency for newborn assessments to overestimate GA in preterm infants and underestimate GA in growth-restricted infants. LIMITATIONS: Poor study quality and few studies with early ultrasound-based reference. CONCLUSIONS: Efforts in low- and middle-income countries should focus on improving dating in pregnancy through ultrasound and improving validity in growth-restricted populations. Where ultrasound is not possible, increased efforts are needed to develop simpler yet specific approaches for newborn assessment through new combinations of existing parameters, new signs, or technology.