Downward percentile crossing as an indicator of an adverse prenatal environment.
BACKGROUND
Postnatal health sequelae of low birth weight have been attributed to 'poor fetal growth' from inferred adverse prenatal environments; risks augmented by infant growth rates. Identifying prenatal growth-restricting events is essential to clarify pathways and mechanisms of fetal growth.


OBJECTIVE
The specific aim of this investigation was to examine whether an episode of preterm labor may compromise fetal growth.


METHODS
Fetal size at the end of the second trimester and birth were compared among women with uncomplicated pregnancies (n = 3167) and those who experienced an episode of preterm labor (<37 weeks) and subsequently delivered at term (> or =37 weeks, n = 147). Fetal weight estimated from ultrasound measures, and changes in weight standard scores across the third trimester investigated significant centile crossing (>0.67 standard deviation score change).


RESULTS
Fetuses delivered at term after an episode of preterm labor were smaller at birth relative to their peers than at the end of the second trimester, and were 47% more likely to experience clinically significant downward centile crossing (p < 0.05) than their peers (OR 1.47, 95% CI 1.04-2.07).


CONCLUSIONS
An episode of preterm labor may signal an adverse prenatal environment for term-delivered neonates. Epidemiologically silent events in the natural history of pregnancy are an understudied source of fetal growth compromise as inferred by small birth size among peers.
Lampl
Michelle
M
Department of Anthropology, Emory University, Atlanta, GA 30323, USA. mlampl@emory.edu
Gotsch
Francesca
F
Kusanovic
Juan Pedro
JP
Espinoza
Jimmy
J
Gonçalves
Luis
L
Gomez
Ricardo
R
Nien
Jyh Kae
JK
Frongillo
Edward A
EA
Romero
Roberto
R
D000328:Adult; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D007752:Obstetric Labor, Premature; D016017:Odds Ratio; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D011295:Prenatal Care; D012727:Sex Characteristics