A recent study has suggested that pregnant women exposed to poor quality indoor air – including tobacco smoke – can place unborn babies at risk of premature birth, dangerously low birth weight, and acute breathing difficulties.
The research was conducted by paediatricians at the University of Cape Town and published in BMJ Open Respiratory Research.
In their analysis of data from 1 143 live births within the Drakenstein Child Health Study – one of Africa’s largest birth cohorts – the scientists found that 17% of babies were born prematurely, 15% suffered from low birth weight, and 7% experienced immediate respiratory distress at birth.
Crucially, said the team, the research proved that infants exposed to high levels of coarse particulate matter while in the womb were nearly twice as likely to suffer from respiratory distress, while elevated carbon monoxide levels trended towards more than doubling the odds of a newborn suffocating at birth.
Furthermore, active maternal smoking was directly linked to significantly lower birth weights in newborns.
The findings come from a peri-urban South African setting where household air pollution remains tragically pervasive despite widespread grid electrification. In an alarming paradox, while 93% of the households surveyed had access to electricity, many families were forced to rely on cheap fossil fuels for daily cooking and heating.
As a result, almost half of all domestic properties recorded particulate matter and benzene – a highly toxic volatile organic compound – levels well above acceptable ambient safety standards.
The study also exposed a rampant tobacco epidemic among expectant mothers. Nearly one-third, or 32%, of the pregnant women monitored were active smokers: 45% were confirmed as passive smokers exposed to second-hand smoke, verified objectively through biochemical urine cotinine testing.
Lead researcher Professor Aneesa Vanker, from UCT’s Department of Paediatrics and Child Health, warned that the findings reinforce the desperate need to mitigate environmental hazards during gestation. She said toxic airborne pollutants are particularly insidious because they can readily cross the protective placental barrier, directly disrupting foetal development and stunting lung growth well before birth.
Unlike previous studies that relied on unreliable, self-reported data from participants, Vanker and her colleagues – Dr Kirsty Brittain, Dr Whitney Barnett, and Professor Heather Zar – meticulously measured multiple household pollutants directly inside the families’ homes, capturing precise levels of nitrogen dioxide, sulphur dioxide, carbon monoxide, and volatile organic compounds.
The definitive data underscore an urgent requirement for aggressive public health interventions and policy changes aimed at expanding genuine access to clean energy, they said.
Experts are now calling for heavily funded antenatal campaigns to educate families on the dangers of smoking and household pollution, saying preventing these toxic exposures before and during pregnancy can safeguard children from life-long respiratory illnesses.
Study details
Antenatal environmental exposure to indoor air pollution and environmental tobacco smoke: association with birth outcomes in an African birth cohort
Aneesa Vanker, Kirsty Brittain, Whitney Barnett, Heather Zar.
Published in BMJ Open Respiratory on 17 June 2026
Abstract
Indoor air pollution (IAP) and environmental tobacco smoke exposure (ETS) are important antenatal environmental exposures that may adversely impact birth outcomes.
Objectives
To investigate the impact of IAP and ETS during pregnancy on birth outcomes including respiratory distress in an African birth cohort, the Drakenstein Child Health Study.
Setting
Prospective cohort study conducted in a periurban setting in sub-Saharan Africa within a large birth cohort.
Participants
Consenting pregnant women (n=1137) enrolled between 20 and 28 weeks’ gestation, with 1143 live births included in the analysis. Participants were recruited antenatally, with inclusion based on residency in the study area and availability of exposure and outcome data.
Primary and secondary outcome measures
Primary exposures included antenatal IAP (particulate matter (PM10), carbon monoxide (CO), nitrogen dioxide, sulphur dioxide, volatile organic compounds) and ETS (maternal urine cotinine). Outcomes included birth anthropometry, prematurity, low birth weight and neonatal respiratory distress.
Results
Among 1143 live births, 17% were premature, 15% had low birth weight and 7% had respiratory distress. Maternal active smoking was associated with reduced weight-for-age z-scores (WfAz; β −0.54; p<0.001). Babies exposed to PM10 above ambient standards were 1.88 times more likely to experience respiratory distress compared with those with exposure below ambient standards (p=0.058). Similarly, exposure to CO above ambient standards was associated with a trend towards a doubled odds of respiratory distress in babies at birth (OR: 2.19 (0.97 to 4.98); p=0.061).
Conclusions
Antenatal exposure to IAP and ETS is associated with adverse birth outcomes, including impaired growth and increased risk of respiratory distress. These findings support the need for targeted public health interventions to reduce exposure during pregnancy and highlight the importance of improving air quality to mitigate long-term respiratory health risks.
See more from MedicalBrief archives:
Sooty air pollution particles reaching the placenta
Air pollution hot spots link to congenital birth anomaly – SAMRC study
South African children face health harms from household fuels, pollutants
Dramatic health benefits following air pollution reduction
Just a cigarette a day in pregnancy doubles Sudden Infant Death risk