Decreased term and postterm birthweight in the United States: impact of labor induction.
OBJECTIVE
We sought to assess recent trends in falling mean birthweight (BW) and gestational age (GA) among US non-Hispanic white singleton live births >or=37 weeks of gestation and the contribution of increased rates of induction to these trends.


METHODS
This was an ecological study based on US vital statistics from 1992 through 2003.


RESULTS
From 1992 through 2003, mean BW fell by 37 g, mean GA by 3 days, and macrosomia rates by 25%. Rates of induction nearly doubled from 14% to 27%. Our ecological state-level analysis showed that the increased rate of induction was significantly associated with reduced mean BW (r = -0.54; 95% confidence interval [CI], -0.71 to -0.29), mean GA (r = -0.44; 95% CI, -0.65 to -0.17), and rate of macrosomia (r = -0.55; 95% CI, -0.74 to -0.32).


CONCLUSIONS
Increasing use of induction is a likely cause of the observed recent declines in BW and GA. The impact of these trends on infant and long-term health warrants attention and investigation.
Zhang
Xun
X
Department of Pediatrics, McGill University Faculty of Medicine, Montreal, Quebec, Canada.
Joseph
K S
KS
Kramer
Michael S
MS
D000328:Adult; D001724:Birth Weight; D002585:Cesarean Section / Q000009:adverse effects / Q000706:statistics & numerical data; D016001:Confidence Intervals; D016208:Databases, Factual; D005260:Female; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007226:Infant Mortality / Q000639:trends; D007231:Infant, Newborn; D007233:Infant, Postmature; D007751:Labor, Induced / Q000009:adverse effects / Q000706:statistics & numerical data*; D016014:Linear Models; D008423:Maternal Age; D015999:Multivariate Analysis; D010298:Parity; D011247:Pregnancy; D047928:Premature Birth; D012189:Retrospective Studies; D018570:Risk Assessment; D047929:Term Birth; D014481:United States / Q000453:epidemiology; D014798:Vital Statistics; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult