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Climate change is impacting babies’ birth weight

According to a new study, exposure to cold or heat stress, particularly in the latter stages of pregnancy, leads to children being too large or too small for their gestational age.

Last year was the hottest on record by an enormous margin, with the Earth 1.48°C warmer than pre-industrial levels and dangerously close to the 1.5°C limit set during the 2015 Paris Agreement.

In 2023, the average global temperature was 0.17°C higher than in 2016, the previous hottest year on record.

Though nowhere near as catastrophic as they’re set to be if we cross the threshold – think, an uptick in insect-borne diseases, stresses on food production, and the eradication of entire ecosystems – the repercussions of this are already palpable, with recent months a flurry of extreme weather, natural disasters, biodiversity loss, droughts, and wildfires.

Aside from the deeply concerning environmental impacts of global warming, rising temperatures are also drastically affecting human health.

As we know, the ecological emergency is altering the way our brains function, augmenting the death rate from cardiovascular and respiratory diseases, and weakening our immune systems.

Not only this, but according to a new study, it’s taking its toll on people who have yet to be born.

Carried out by experts from the Curtin School of Population Health in Perth, the research examined more than 385,000 pregnancies in Western Australia between 2000 and 2015.

Using the Universal Thermal Climate Index (UTCI), which describes the physiological comfort of the human body under specific conditions, it focused on exposure to cold or heat stress in the latter stages of pregnancy and found both to significantly increase the risk of abnormal birth weight.

The risk became greater for certain groups, including non-white mothers, male births, pregnancies in those aged 35 or over, people living in rural areas, and smokers.

As it states, children being too large or too small for their gestational age can impact their development and chances of survival, as well as amplify their vulnerability to illness in adulthood.

‘Thermal stress exposures increase dehydration and induce oxidative stress and systemic inflammatory responses, leading to adverse reproductive and foetal health outcomes,’ says co-author Dr Sylvester Dodzi Nyadanu.

‘There needs to be further studies into what interventions will achieve better results for parents and babies – especially in the specific vulnerable sub-populations identified in our study.’

The study builds on growing evidence of the threat posed by climate change to reproductive health.

Other analyses have uncovered that exposure to smoke from wildfires doubles the risk of severe birth defects and that air pollution from burning fossil fuels, even at low levels, is bringing about a reduction in fertility.

‘From the very beginning, from preconception, through early childhood into adolescence, we’re starting to see important impacts of climate hazards on health,’ says Professor Gregory Wellenius of the Boston University School of Public Health.

‘This is a problem that affects everybody, everywhere. These extreme events are going to become even more likely and more severe with continued climate change [and this research shows] why they’re important to us, not in the future, but today.’

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