Neonatal morphometry. Relation to obstetric, pediatric, and menstrual estimates of gestational age
M. P. Dombrowski, H. M. Wolfe, Y. W. Brans, A. A. Saleh and R. J. Sokol
Department of Obstetrics and Gynecology, Wayne State University/Hutzel Hospital, Detroit, Mich.
OBJECTIVE--To determine gestational age-dependent neonatal morphometrics
based on last menstrual periods (LMPs), Ballard examinations, and obstetric
estimates of gestational age. DESIGN, SETTING, AND
PARTICIPANTS--Cross-sectional survey of 38,818 live-born neonates at a
tertiary care center in Detroit, Mich. SELECTION PROCEDURES--Consecutive
sample of all viable, structurally normal, singleton neonates delivered at
Hutzel Hospital from 1984 through 1991. MEASUREMENTS/MAIN RESULTS--Neonatal
weights, lengths, and head circumferences were recorded at birth.
Gestational age-dependent morphometrics were based solely on LMPs and
compared with those based on obstetric estimates (using LMPs corrected by
fetal ultrasound). Ballard examination had an 85.4% concurrence (within 14
days) with obstetric estimates of gestational age, but only a 69.9% (P less
than .0001) agreement with LMP. Dating only by LMP significantly
overestimated the prevalence of prematurity (odds ratio [OR], 1.3; 99%
confidence interval [CI], 1.3 to 1.4) and postmaturity (OR, 5.0; 99% CI,
4.6 to 5.4), distorting apparent growth patterns, especially for preterm
neonates. In contrast to previous studies based solely on LMPs,
morphometric measurements increased beyond 40 weeks when dated by obstetric
estimates. CONCLUSIONS--Gestational age-dependent neonatal morphometrics
should not be based solely on LMPs.
