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

Fetal growth restriction in association with particulate air pollution before and during pregnancy... • To assess the shape of the association • To compare the effects on birth weight w

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

pregnancy

What is the clinical meaning of fetal

growth restriction

Why should we study it?

Circulation 2005;112:1414-1418

Lancet 2005;365:1484-1486

Blood pressure and birth weight

Am J Epidemiol 2007;166:413–420

• 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

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

Exposure interpolation and weigthing

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.

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

3149 3243 3326

Birth weight changes calculated for a 10 µg/m³

increase

Adjusted for maternal age, infant gender, parity, season, socioeconomic status, gestational age, time

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

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

14 d 3 m 6 m 9 m Conception Pregnancy

0.8 1.0 1.2 1.4

<32 w

32-36 w

> 36 w

p for interaction air pollution by gestation < 0.0001

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

Does PM exposure during conception or pregncancy the risk of preterm delivery?

No significant association (also no trend)

Perspective: comparison with other

exposures

Systematic review of other smoke related

exposures

2008;22:162-71.

daily dose of fine particulate matter from air pollution along with comparison estimates of ETS, biomass and cigarette smoke.

Circulation 2009;120:941-948)

-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

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

• 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