Women who live in areas with high air pollution give birth to smaller babies compared to those who live in greener areas, finds a study.

Women living in greener areas gave birth to babies with slightly higher birth weight (27g heavier on average) than mothers living in less green areas, according to the research presented at the European Respiratory Society International Congress in Milan, Italy.

Children with low birth weight face a higher risk of asthma and higher rates of chronic obstructive pulmonary diseases (COPD) as they grow older.

“The time when babies are growing in the womb is critical for lung development. We know that babies with lower birth weight are susceptible to chest infections, and this can lead to problems like asthma and COPD later on,” said Robin Mzati Sinsamala, a researcher in the Department of Global Public Health and Primary Care at the University of Bergen (UiB) in Norway.

Our results suggest that pregnant women exposed to air pollution, even at relatively low levels, give birth to smaller babies. They also suggest that living in a greener area could help counteract this effect.

It could be that green areas tend to have lower traffic that plants help to clear the air of pollution, or green areas may mean it’s easier for pregnant women to be physically active. he added.

The study included 4,286 children and their mothers living in five European countries (Denmark, Norway, Sweden, Iceland and Estonia).

Researchers compared the babies' birth weights by taking into account factors that affect birth weight, such as the mother’s age, whether the mother smoked or had any other health conditions. They also take note of the density of vegetation and the presence of pollutants in the air.

“There is a need to reduce air pollution and make towns and cities greener to help protect babies and their developing lungs from potential harm,” said researchers.