Prenatal exposure to traffic-related air pollution and ultrasound measures of fetal growth in the INMA Sabadell cohort.
BACKGROUND
Few studies have used longitudinal ultrasound measurements to assess the effect of traffic-related air pollution on fetal growth.


OBJECTIVE
We examined the relationship between exposure to nitrogen dioxide (NO2) and aromatic hydrocarbons [benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene (BTEX)] on fetal growth assessed by 1,692 ultrasound measurements among 562 pregnant women from the Sabadell cohort of the Spanish INMA (Environment and Childhood) study.


METHODS
We used temporally adjusted land-use regression models to estimate exposures to NO2 and BTEX. We fitted mixed-effects models to estimate longitudinal growth curves for femur length (FL), head circumference (HC), abdominal circumference (AC), biparietal diameter (BPD), and estimated fetal weight (EFW). Unconditional and conditional SD scores were calculated at 12, 20, and 32 weeks of gestation. Sensitivity analyses were performed considering time-activity patterns during pregnancy.


RESULTS
Exposure to BTEX from early pregnancy was negatively associated with growth in BPD during weeks 20-32. None of the other fetal growth parameters were associated with exposure to air pollution during pregnancy. When considering only women who spent < 2 hr/day in nonresidential outdoor locations, effect estimates were stronger and statistically significant for the association between NO2 and growth in HC during weeks 12-20 and growth in AC, BPD, and EFW during weeks 20-32.


CONCLUSIONS
Our results lend some support to an effect of exposure to traffic-related air pollutants from early pregnancy on fetal growth during mid-pregnancy..
Aguilera
Inmaculada
I
Centre for Research in Environmental Epidemiology, Barcelona, Spain. iaguilera@ creal.cat
Garcia-Esteban
Raquel
R
Iñiguez
Carmen
C
Nieuwenhuijsen
Mark J
MJ
Rodríguez
Agueda
A
Paez
Montserrat
M
Ballester
Ferran
F
Sunyer
Jordi
J
D000293:Adolescent; D000328:Adult; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity; D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis; D015331:Cohort Studies; D004781:Environmental Exposure; D005260:Female; D047109:Fetal Development / Q000187:drug effects; D006801:Humans; D006841:Hydrocarbons, Aromatic / Q000032:analysis / Q000633:toxicity; D007231:Infant, Newborn; D008297:Male; D009585:Nitrogen Dioxide / Q000032:analysis / Q000633:toxicity; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000000981:diagnostic imaging*; D013030:Spain; D014186:Transportation; D016216:Ultrasonography, Prenatal; D014504:Urban Health; D055815:Young Adult
D000393:Air Pollutants; D006841:Hydrocarbons, Aromatic; D009585:Nitrogen Dioxide