Fetal growth restriction in association with particulate air pollution before and during pregnancy potx

www.milieu-en-gezondheid.be
Fetal growth restriction in association with
particulate air pollution before and during
pregnancy

www.milieu-en-gezondheid.be
What is the clinical meaning of fetal
growth restriction
Why should we study it?
www.milieu-en-gezondheid.be
Circulation 2005;112:1414-1418
www.milieu-en-gezondheid.be
Lancet 2005;365:1484-1486
www.milieu-en-gezondheid.be
Blood pressure and birth weight
Am J Epidemiol 2007;166:413–420
www.milieu-en-gezondheid.be
Aims
• To study the risk of fetal growth restriction in associaotin
with outdoor PM10 concentrations at the mothers’
residence.
• To study potential effect modification by gestational
duration.
• To assess the shape of the association
• To compare the effects on birth weight with biomass
exposure (develomental countries), ETS and maternal
smoking during pregnancy.
www.milieu-en-gezondheid.be
Methods (1)
• SPE data on 345,081 singleton newborns
• Interpolation method and population weighted

on the level of municipality.
• Calculation of exposure for each trimester,
period (14 days) around conception and 80 days
before conception
• Polynomial models to study the shape of the
association
• Systematic comparison with ETS, smoking,
biomass.
www.milieu-en-gezondheid.be
Exposure interpolation and weigthing
www.milieu-en-gezondheid.be
Methods (2)
Based on meta-analytic data comparison
estimates for biomass, ETS exposure and
maternal smoking were plotted against
estimated average daily dose of fine
particulate matter from these exposures.
www.milieu-en-gezondheid.be
Characteristics
Characteristic Mean birth weight (g)
Gender
Male
Female
3267
3397
Season
Cold
Warm
3328
3338

SES
Low
Medium
High
3323
3340
3360
Parity
1
2
3
≥ 4
3263
3392
3408
3382
Gestation age (weeks)
< 32
32-36
> 36
1296
2332
3371
Maternal age (years)
< 20
20-24
25-29
30-34
35-39
3149

3243
3326
3375
3359
www.milieu-en-gezondheid.be
Birth weight changes calculated for a 10 µg/m³
increase
Adjusted for maternal age, infant gender, parity,
season, socioeconomic status, gestational age, time
trend
Period Estimate (95% CI)
Gestation Estimate (95% CI)
Conception
(14 days)
-5.74 -7.27 -4.22 <32
32-36
>36
0.11
-13.1
-5.59
-16.2
-23.3
-7.14
16.5
-2.83
-4.04
Trimester 1 -12.6 -15.0 -10.3 <32
32-36
>36
21.2

-38.6
-12.3
-6.49
-54.5
-14.7
48.8
-22.8
-10.0
Trimester 2 -14.2 -16.6 -11.9 <32
32-36
>36
16.5
-33.0
-14.1
-11.4
-49.4
-16.5
44.5
-16.5
-11.7
Trimester 3 -13.0 -15.5 -10.5 <32
32-36
>36
8.30
-18.7
-13.4
-11.1
-33.9
-15.9
27.7

-3.46
-10.9
Overal
Pregnancy
-17.8 -20.6 -15.1 <32
32-36
>36
21.4
-17.8
-17.7
-8.7
-20.6
-20.6
51.5
-15.1
-15.0
www.milieu-en-gezondheid.be
Adjusted for maternal age, infant gender, parity,
season, socioeconomic status, gestational age, time
trend
Odds ratio for small for gestational age calculated for a 10 µg/m³
increase in exposure around conception and during pregancy
0.7
0.8
0.9
1.0
1.1
1.2
1.3
<32 w

32-36 w
> 36 w
p for interaction air pollution by gestation < 0.0001
Odds ratio
14 d 3 m 6 m 9 m
Conception Pregnancy
www.milieu-en-gezondheid.be
0.8
1.0
1.2
1.4
<32 w
32-36 w
> 36 w
p for interaction air pollution by gestation < 0.0001
Odds ratio
Independent odds ratios for small for gestational age calculated for a
10 µg/m³ increase in exposure around conception and during pregancy
Adjusted for maternal age, infant gender, parity,
season, socioeconomic status, gestational age, time
trend and exposure during conception / pregnancy.
14 d 3 m 6 m 9 m
Conception Pregnancy
www.milieu-en-gezondheid.be
Does PM exposure during conception or
pregncancy the risk of preterm delivery?
No significant association (also no trend)
www.milieu-en-gezondheid.be
Perspective: comparison with other
exposures

www.milieu-en-gezondheid.be
Systematic review of other smoke related
exposures
•Biomass: Pope et al. Epidemiol Rev. 2010;32:70-81.
•ETS: Salmasi et al. Acta Obstet Gynecol Scand. 2010;89:423-41.
• Maternal smoking: Jaddoe et al. Paediatr Perinat Epidemiol.
2008;22:162-71.
• We plotted decreases in birth weight against estimated average
daily dose of fine particulate matter from air pollution along with
comparison estimates of ETS, biomass and cigarette smoke.
• Assumptions 18 m³/day, dose cigarette 12 mg PM
10 (Pope et al.
Circulation 2009;120:941-948)
www.milieu-en-gezondheid.be
-1 0 1 2
-250
-200
-150
-100
-50
0
air pollution
ETS
biomass
<5 cig
5-9 cig
>9 cig
0.21-0.40 mg/d
0.36-0.48 mg/d
4.5 mg/d

70 mg/d
20 mg/d
130 mg/d
estimated daily dose of PM
10,
mg/day
Reduction, birth weight g
The baseline estimated dialy dose assumes an inhalation rate of 18 m³/day and a dose of 12 mg per cigarette.
Comparison with smoking, ETS and biomass
exposure
www.milieu-en-gezondheid.be
Conclusions
• We noted associatons between fetal growth restrictions
and particulate air pollution
• Especially in preterm born infants.
• Effects not explained by preterm delivery
• Assuming causality; lowering PM10 exposure by 10
µg/m³ would avoid 19% of SGA neonates born between
32-36 weeks of pregnancy and 5% of SGA children born
ad term.
• Effects in highest exposure group in the range of ETS