Climate change could be impacting when girls in India get their first period: Study

Researchers analysed data gathered through 'Demographic and Health Surveys' (DHS) during 1992-93 and 2019-21, along with climate data from NASA.

New Delhi: Climate change could be affecting when girls get their first periods, with higher humidity linked with an earlier onset and higher temperatures with a delayed one, according to a study.

Researchers from institutes in Bangladesh, including the North South University, analysed data gathered through 'Demographic and Health Surveys' (DHS) during 1992-93 and 2019-21, along with climate data from NASA.

Over 23,000 responses from 1992 and 45,300 from 2019 were analysed.

Results of the analysis, published in the journal PLOS Global Public Health, showed that girls across most states in India were starting to menstruate at a younger age, except those in Maharashtra, where the onset of periods among girls was found to be delayed.

The authors wrote, "This study investigates the factors influencing the age of menarche in various Indian states over a quarter century from 1992 to 2019, with the aim of understanding how climate change and demographic factors have shaped menarche timing." "Higher specific humidity was associated with earlier onset of menarche, whereas higher temperatures correlated with delayed onset," they wrote.

The researchers added that the age of menarche -- start of menstruation -- is changing in girls across the world, with a younger age at menarche seen especially in the second half of the 20th century.

Previous studies have attributed the trend to varied factors -- environmental ones include climate change and air pollution, while others are related to obesity, such as BMI.

The study found that rising humidity generally advances the age of menstruation by altering underlying health conditions.

However, the link between higher temperatures and a delayed onset of periods among girls in Maharashtra could reflect a physiological stress due to prolonged exposure to heat, which can impact how hormones get regulated and delay puberty, the researchers said.

They called for continued monitoring of climate impacts on health, essential for understanding and mitigating the effects of environmental changes on menarche timing.

The team also found that higher education could be linked with an earlier menarche, indicating demographic influences.

"The findings highlight the need for public health interventions that improve nutrition, healthcare access and educational programs to promote health awareness," they wrote.

Run by the US-based company ICF International, the DHS programme conducts nationally representative surveys in low- and middle-income countries every five years, looking at maternal and child health, among other aspects.