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Blair J. Wylie 1,4, Neeru Singh 2, Mrigendra P. Singh 2, Eleanne van Vliet 3, Patrick L. Kinney 3, William B. MacLeod 4, Kojo Yeboah-Antwi 4, Davidson.

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Presentation on theme: "Blair J. Wylie 1,4, Neeru Singh 2, Mrigendra P. Singh 2, Eleanne van Vliet 3, Patrick L. Kinney 3, William B. MacLeod 4, Kojo Yeboah-Antwi 4, Davidson."— Presentation transcript:

1 Blair J. Wylie 1,4, Neeru Singh 2, Mrigendra P. Singh 2, Eleanne van Vliet 3, Patrick L. Kinney 3, William B. MacLeod 4, Kojo Yeboah-Antwi 4, Davidson H. Hamer 4 1 Division of Maternal-Fetal Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States; 2 National Institute for Malaria Research Field Station, Jabalpur, India; 3 Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York, NY; 4 Center for International Health and Development, Boston University, Boston, MA, United States. Impact of biomass cook smoke exposure on birth weight in central east India ► Exposure to high levels of smoke is a daily reality for 3 billion households worldwide using solid biomass cook fuels (e.g. dung, straw, wood, charcoal) ► Biomass burning releases numerous noxious pollutants including: - suspended particulate matter (e.g., PM 2.5 ) - carbon monoxide (CO) - nitrous oxide (N 2 0) ► The World Health Organization estimates indoor air pollution is 2 nd largest environmental killer (behind unsafe water), accounting for 1 : million annual deaths - 2.7% of global burden of disease ► 2 recent studies suggest exposure to cook smoke from combustion of biomass fuels during pregnancy reduces birth weight 2,3 - Birth weights reduced on average by g among women cooking with biomass vs. those cooking with efficient fuels (natural gas, electricity) - Effect similar in magnitude to maternal smoking and greater than that associated with environmental tobacco exposure b Table 1: Cohort characteristics, n=660 BACKGROUND STUDY DESIGN RESULTS CONCLUSIONS AIM: To evaluate the effect of prenatal exposure to various cook fuels on birth weight HYPOTHESIS: Birth weights will be greatest among infants born to mothers cooking with the most efficient fuel (gas) LOCATION: ● State of Jharkhand, India at 3 hospitals: - Sadar Hospital, Ranchi - Civil Hospital, Gumla - Ursula Mission Hospital, Konubir DESIGN: Secondary analysis of a cohort of pregnant women recruited at the time of delivery to define the burden of malaria in pregnancy in central east India ● Enrollment over 12-month period (2007) ● Multiple gestations and stillbirths excluded from analysis PROCEDURES by trained research nurses: ● Detailed maternal interview assessing primary cook fuel used, hours spent cooking and number of other potential covariates associated with birth weight ● Maternal blood pressure, height, weight measured upon enrollment ● Infants weighed at delivery with digital scale; gestational age assessed with modified Ballard ● Maternal hemoglobin quantified by capillary finger stick (Hemocue) ● Placental malaria diagnosed by Giemsa-stained smear of placental blood STATISTICAL ANALYSIS: Mean birth weights compared using ANOVA and proportion of low birth weight (LBW) compared by chi- square among singleton live-born infants born to mothers in the 3 most common cook fuel groups. Logistic regression was used to compute odds ratios (ORs) for LBW by fuel type, adjusting for other BW determinants and potential confounders if such covariates were significantly associated with both exposure and outcome. Table 1: Cohort characteristics, n=660 Primary cook fuel † Mean birth weight, grams (STD) Low birth weight n (%) Charcoal (n=105)2615 (388.2)32 (30.5%) Wood (n=460)2770 (453.5)86 (18.7%) Gas (n=95)2774 (437.1)17 (17.9%) p=0.0130*p=0.005* Figure 1: Primary cooking fuel used Jharkhand, India- highlighted in yellow (1) World Health Organization. New country-by-country data show in detail impact of environmental factors on health. Accessed online at (2) Boy E, Bruce N, Delgado H. Birth weight and exposure to kitchen wood smoke during pregnancy in rural Guatemala. Environmental Health Perspectives. 2002; 110(1): (3) Mishra V, Dai Z, Smith K, Mika L. Maternal exposure to biomass smoke and reduced birth weight in Zimbabwe. Annals of Epidemiology. 2004; 14(10): (4) Bhattacharya SC, Albina DO, Abdul Salam P. Emission factors of wood and charcoal-fired cookstoves. Biomass and Bioenergy. 2002;23(6): Indian woman tending indoor cooking fire n=674 † Only 3 most common cook fuels analyzed as sample size in other groups too small for meaningful analyses. * Charcoal group differs significantly from other two groups. Gas and wood do not differ significantly from each other. Charcoal § n=105 Wood § n=460 Gas § n=95 Mean hours spent cooking* (STD)2.7 (0.8)3.5 (1.0)2.7 (1.0) Primigravid* † 32 (30.5%)208 (45.2%)45 (47.4%) Age categories <20 years years >35 years 8 (7.6%) 95 (90.5%) 2 (1.9%) 42 (9.1%) 388 (84.4%) 30 (6.5%) 9 (9.5%) 84 (88.4%) 2 (2.1%) Mean body mass index (STD)20.6 (2.2)20.5 (2.2)20.9 (2.8) Primary occupation* Housework Agriculture Other 100 (95.2%) 0 (0%) 5 (4.8%) 330 (71.7%) 64 (13.9%) 66 (14.4%) 83 (87.4%) 2 (2.1%) 10 (10.5%) Married105 (100%)460 (100%)95 (100%) No formal schooling* † 47 (44.7%)139 (30.2%)10 (10.5%) Smoked in pregnancy0 (0%) 0 (%) Caste † General SC/ST/OBC ¶ 26 (24.7%) 79 (75.2%) 98 (21.3%) 362 (78.7%) 51 (53.7%) 44 (46.3%) Floor material* † Earth/sand Cement/vinyl tiles 57 (54.3%) 48 (45.7%) 401 (87.2%) 59 (12.8%) 15 (15.8%) 80 (84.2%) Median gestational age at birth (IQR)38 (38-40) Anemia at delivery (Hgb < 11 g/dL) † 69 (66.4%)274 (60.2%)39 (41.5%) Placental malaria1 (1.0%)14 (3.1%)0 (0%) Hypertension at delivery26 (24.8%)133 (28.9%)23 (24.2%) § Only 3 most common cook fuels analyzed as sample size in other groups too small for meaningful analyses. * p < 0.05 for charcoal vs wood. † p <0.05 for charcoal vs gas. ¶ SC= scheduled castes; ST= scheduled tribes; OBC+ other backward castes. Grouped together as the Government of India recognizes these 3 castes for positive discrimination in education and jobs. Table 2: Birth weight by cook fuel exposure Unadjusted OR (95%CI) Adjusted OR (95% CI) Charcoal vs other fuel 1.92 ( )1.72 ( ) † Charcoal vs wood1.91 ( )1.76 ( ) § Charcoal vs gas2.01 ( )1.52 ( )* Table 3: Odds of LBW †Adjusted for gravidity, education, anemia, home ownership, hours spent cooking, occupation, floor material. §Adjusted for gravidity, education, home ownership, hours spent cooking, occupation, floor material. *Adjusted for caste, gravidity, education, anemia, home ownership, floor material. Use of charcoal was associated with reduced birth weights among infants born to this cohort of Indian women. The magnitude of reduction is similar to that associated with maternal smoking. The risk of LBW was increased when charcoal users were compared with users of other fuels. In the transition to modern fuels, charcoal is a popular alternative to wood as it releases less smoke, blackens pots less, and requires less fire tending; yet charcoal- fired stoves emit more nitrous oxide and carbon monoxide compared with wood 4. These differences may account for our findings. Alternately, it is possible that uncontrolled confounding may explain the association between charcoal use and birth weight– with charcoal use merely a marker of another exposure linked with birth weight reduction. Policy efforts directed at improving energy efficiency for households in the developing world should consider the impact of cook fuels on the developing fetus. Further research is needed to clarify this relationship and identify the safest fuels. REFERENCES For further information, contact: Blair Wylie at Mass General Hospital


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