Effect of Indoor Air Effect of Indoor Air Pollution from Biomass Pollution from Biomass

and Solid fuel and Solid fuel Combustion on Combustion on Symptoms of Symptoms of

Preeclampsia/Eclampsia Preeclampsia/Eclampsia in Indian Women in Indian Women 

Sutapa Agrawal

Public Health Foundation of India

New Delhi, INDIA

Session 3049.0: Women’s health I 142nd American Public Health Association Annual Meeting and Exposition

IntroductionIntroduction

• Pre-eclampsia is a pregnancy-induced hypertensive disorder – characterized by high blood pressure and proteinuria

after the 20th week of pregnancy.

• Eclampsia is the occurrence of generalized seizures/convulsions/ and/or unexplained coma – during pregnancy or postpartum in a pre-eclamptic

woman in the absence of other neurologic conditions.

Why Preeclampsia/eclampsia Why Preeclampsia/eclampsia is is important

• Preeclampsia/eclampsia is a potentially fatal disorder in pregnant women and associated with adverse pregnancy outcomes

– perinatal death, preterm birth, and intrauterine growth retardation which also remains one of the leading causes of maternal mortality and morbidity worldwide.

Why Preeclampsia/eclampsia is important

• Besides, its association with the established risk factors an emerging risk factor of preeclampsia/ eclampsia is indoor air pollution (IAP) particularly in low and middle income countries.

Indoor air pollution in developing country

• Over 200 studies have measured air pollution levels in developing country households across all WHO regions

Effect of Indoor Air Pollution

• These studies shows– extreme exposures in solid cooking fuel use in rural

and urban settings, often manifold higher than recommended WHO Air Quality Guidelines

– The burning of solid fuels indoors in open fires or traditional cooking stoves (chulhas) results in high levels of toxic pollutants in the kitchen area.

– Poor ventilation worsens the adverse health effects of indoor air pollution

Indoor air pollution Exposure in India

• According to India’s third National Family Health Survey (NFHS-3, 2005–2006) – 90% of rural and 32% of urban households (overall

71%) in India use biomass and solid cooking fuels that generate smoke and unhealthy conditions when inhaled.

– Additionally, 74% of households cook their meals inside the house.

Indoor air pollution Exposure in India

– About one-third of households that cook inside the house do not have a separate room for cooking.

– In both urban and rural areas, 9 in 10 households that use solid fuels and cook on an open fire also lack chimneys to divert smoke

According to India’s third National Family Health Survey (NFHS-3, 2005–2006)

Objectives of the study

We aim to investigate the association between exposure to indoor air pollution from biomass and solid fuel combustion and symptoms suggestive of preeclampsia/ eclampsia in Indian women.

Methods and Materials

• Cross sectional Data from –India’s third and latest round of National

Family Health Survey (NFHS-3) conducted in 2005-06.

• NFHS-3 collected • Data from a nationally representative

probability sample of 124, 385 women (62.6%) age 15-49 residing in 109,041 households.

Outcome MeasureOccurrence of preeclampsia/eclampsia symptoms

Following the World Health Organisation [2007] and National Institute for Health and Care Excellence [2010] guidelines, we created a dichotomous indicator of PE/E

Occurrence of preeclampsia/ Occurrence of preeclampsia/ eclampsia symptomseclampsia symptoms

• Women who gave birth during the last five years (n=39657) were asked about the health problems that they experienced during their last pregnancy:

• Women who reported both difficulty with vision during daylight and swelling of the legs, body, or face, were coded as having symptoms suggestive of preeclampsia,

• Those who additionally reported experiencing convulsions (not from fever) were coded as eclamptic.

Limitation of the outcome measure

It was not possible to confirm clinical diagnosis of the symptoms of PE/E.

-Data on blood pressure and proteinuria during pregnancy, which are typical clinical diagnostic markers of pre-eclampsia, were not available in the NFHS-3.

-Data on physician reported diagnosis of convulsions/seizures were not available in the NFHS-3 to verify a self-reported diagnosis.

Predictor variable

• Households were categorized into two types based on the type of cooking fuel use:

Biomass (such as wood, straw/shrubs/grass, agricultural crop waste, dung cakes, or others) and solid fuel use (such as coal/lignite and charcoal)

- 78% of the women in India live in households using biomass and solid fuels

Clean fuel use (such as kerosene, LPG/natural gas, biogas, or electricity)

-22% of the women in India live in households using cleaner fuels

Control Variables

We controlled for three groups of potential confounders.

The confounders and covariates were selected on the basis of previous knowledge of their association with preeclampsia/ eclampsia

Maternal factors

– Parity (1, 2–3, 4 and above)

– Type of pregnancy (singleton, twin)

– History of a terminated pregnancy (no, yes)

Health- and lifestyle-related factors

– BMI (categories),

– Current tobacco smoking (no, yes)

– Alcohol use (no, yes)

– Self-reported diabetes (no, yes)

– Self reported asthma (no, yes)

– Anemia level (not anemic, mild, moderate, severe)

Socio-demographic predictors

– Age (15–29, 30–39, 40–49 years)– Education (no education, primary, secondary, higher)– Religion (hindu, muslim, christian, sikhs, others)– Caste (scheduled castes, scheduled tribes, other

backward class, others)– Wealth index (measured by an index based on

household ownership of assets and graded as lowest, second, middle, fourth, and highest)

– Place of residence (urban, rural)– Geographic regions (north, northeast, central, east,

west, south)

Statistical AnalysisStatistical Analysis

• Standard descriptive statistics were used

• χ2 tests used to test significant differences in categorical variables

• Fixed effects multivariable logistic regression models were used

– to estimate the association between exposure to cooking smoke and preeclampsia/eclampsia risk.

– State fixed effects were included in the adjusted anaysis, and standard errors were clustered at the primary sampling unit

Statistical Analysis

Sampling weights were used to account for the sample design and to ensure the representativeness of the sample

Analysis conducted using the SPSS statistical software package Version 19 (IBM SPSS Statistics, Chicago, Illinois, USA)

Prevalence of symptoms suggestive of preeclampsia/

eclampsia• The overall prevalence of symptoms

suggestive of preeclampsia/eclampsia was 1.2% (456 out of 39657)

• Prevalence of symptoms suggestive of preeclampsia/eclampsia significantly differ with type of cooking fuel use in the household: - 1.4% among women residing in households using biomass and

solid fuel

- 0.4% among women residing in households using cleaner fuels

A higher prevalence of A higher prevalence of preeclampsia/ eclampsia was preeclampsia/ eclampsia was

reported by women who have/are:reported by women who have/are:

Parity greater than 4 (1.7%); Twin pregnancy (3.1%)

Previously terminated pregnancy (1.4%)

Mild to moderate anemia (1.3–1.5%)

Underweight and normal weight (1.3%)

Current smokers (1.7%); Current drinkers (2.6%)

Diabetics (1.6%); Asthmatics (4.7%)

No education (1.6%); Scheduled tribes (2.2%)

Households belonging to lowest wealth quintile (2.0%)

Residence in rural areas (1.4%)

Residence in central part of India (1.7%)

Effects of cooking smoke on Effects of cooking smoke on preeclampsia/eclampsiapreeclampsia/eclampsia

• Unadjusted analysis

The likelihood of reporting preeclampsia/ eclampsia symptoms were more than three times higher (OR: 3.35; 95% CI: 2.36–4.76; P < 0.0001) among women living in households using biomass and solid fuels for cooking than among those living in households using cleaner fuels for cooking.

Effects of cooking smoke on Effects of cooking smoke on preeclampsia/eclampsiapreeclampsia/eclampsia

Adjusted analysis

• Cooking with biomass and solid fuels still had a large and statistically significant effect (OR: 2.21; 95% CI: 1.26–3.87; P = 0.003) on the likelihood of preeclampsia/ eclampsia symptoms among women.

Major FindingsMajor Findings

• Indoor air pollution from biomass and solid fuel combustion is highly prevalent and is a major public health threat in India

• Higher prevalence and likelihood of self-reported symptoms suggestive of preeclampsia/ eclampsia was noted among women in their last pregnancy with exposure to indoor air pollution .

Our result in context of other Our result in context of other studiesstudies

• Many studies have linked ambient air pollution (mainly outdoor) to gestational hypertension, and preeclampsia in developed countries (van den Hooven et al., 2009, 2011; Rudra et al., 2011; Lee et al., 2012; Pereira et al., 2013; Vinikoor-Imler et al., 2012; Wu et al., 2009, 2011).

Our result in context of other Our result in context of other studiesstudies

– A recent US study found an association between first trimester PM10 and O3 air pollution exposures and increased blood pressure in the later stages of pregnancy (Lee et al., 2012)

– Maternal PM10 exposure was associated with an increased risk of pregnancy-induced hypertension (OR: 1.72; 95% CI, 1.12–2.63, per 10-lg/m3 increase) in 7006 women participating in a prospective cohort study in the Netherlands (van den Hooven et al., 2011).

– An epidemiologic study showed that exposure to local traffic-generated air pollution during pregnancy increases the risk of preeclampsia and preterm birth (Pereira et al., 2013).

Mechanisms

• The biological mechanisms about how indoor air pollution is effecting are not yet well understood partially because the condition is a multisystem disorder of unknown etiology.

Mechanisms

Particulate matter air pollution

is capable of augmenting the development and progression of atherosclerosis and may potentially contribute to hypertension (Brook et al., 2010).

Preeclampsia and vascular atherosclerosis may share common pathways in relation to pollutants (Duckitt and Harrington, 2005; Kaaja and Greer, 2005).

MechanismsMechanisms

Ambient air pollution has been directly correlated with endothelial dysfunction (Tornqvist et al., 2007), a precursor associated with preeclampsia (Steegers et al., 2010).

It is suspected that traffic emissions may also contribute to an anti-angiogenic state (Ejaz et al., 2009) that may in turn contribute to the development of preeclampsia (Young et al., 2010).

Implications of preeclampsia/ eclampsia for prevention of

pregnancy complications in India

• Given that preeclampsia shares many risk factors with cardiovascular disease (CVDs) it is expected that the increase in the CVDs risk factors in women of childbearing age could translate into a higher incidence of preeclampsia and its complications (e.g. eclampsia), thus increasing the risk to pregnant women in India.

• With the target of the Millennium Development Goals in sight, preeclampsia/eclampsia needs to be identified as a priority area in reducing maternal mortality and morbidity in developing countries including India.

Implications of indoor air pollution for prevention of pregnancy

complications in India

To minimize the adverse effect on preeclampsia/eclampsia

•There is an urgent need for public health actions in India

•Vigorous information campaigns to inform people about the risks of exposure to cooking smoke

•Additionally, programs to promote improved cooking stoves designed to reduce exposure to smoke by means of improved combustion and increased ventilation

Strengths of the study

• Study based on large nationally representative dataset – allowed us to examine the effect of indoor air pollution from

biomass and solid fuel combustion on preeclampsia/eclampsia risk in the Indian women of childbearing age.

• A particular strength was that we had individual-level information on socioeconomic status

which allowed for further investigations of the exposures and the outcomes of interest.

• The large sample size provided adequate power to identify various risk factors and compensated for the large ethnic

variations in Indian populations.

Strengths of the study

• The National Family Health Survey -3 was conducted using questionnaire in the native language of the respondent using local, commonly understood terms for pregnancy-related health problems.

A total of 18 languages were used with back translation to English to ensure accuracy and comparability.

Weaknesses

• Case ascertainment was based on self-reported symptoms

• The self-reports may be subjected to recall bias

• Self-reports, especially in rural areas, can be flawed

Weaknesses

• It was also not possible – to identify the gestational onset of

preeclampsia/eclampsia from the given data.

• Limitations also include the cross-sectional study design, – which thereby limits conclusions regarding causality.

– observational findings and uncontrolled confounding cannot be excluded as an explanation for the association.

ConclusionsConclusions

Our findings have important program and policy implications for countries like India, where large proportions of the population rely on polluting biomass fuels for cooking and space heating and have an additional burden of high maternal and infant mortality and morbidity.

Future works Future works

• Research and appropriate policy on indoor air pollution and its health effects such as preeclampsia/ eclampsia

–should be put forth and strengthened in addition to other health effects

• Systematic approach to the development and evaluation of interventions

– for clearer recognition of the interrelationships between poverty and dependence on polluting fuels