Exposure to air pollution during pregnancy is linked to preterm birth, low birth weight, and complications like hypertensive disorders. A recent study shows that the impact extends to mental health, with exposure to pollution nearly quadrupling the risk of postpartum depression. This heightened risk can last up to three years, the latest study revealed.

Higher levels of nitrogen dioxide (NO2,)and inhalable particulate matter (PM10), especially over long periods, are known to raise the risk of various health issues like asthma, heart attack, and stroke. The study published in Science of the Total Environment suggests that these pollutants are also linked to an increased risk of postpartum depression.

"What's really novel about this work is that we were able to extend the examination of depression beyond the first year postpartum, and have shown the sustained effect of air pollution during pregnancy on symptoms of depression all the way through three years postpartum," said Tracy Bastain, senior author of the study in a news release.

The researchers followed up 361 expectant mothers from the start of pregnancy through three years postpartum. The depressive symptoms of the participants were collected one, two, and three years after they gave birth. This data was compared to weekly air pollution measurements near their homes during pregnancy.

Analysis indicates that women exposed to higher levels of NO2 between weeks 13 and 29 of pregnancy had a 3.86 times higher risk of postpartum depression for up to three years. Those exposed to higher levels of PM10 between weeks 12 and 28 also had a similar higher risk (3.88 times). After one year, 17.8% of women had depressive symptoms, 17.5% after two years, and 13.4% after three years.

"Our study actually found a higher percentage of clinically significant depression compared to recent CDC data. That's quite important—that there's probably more postpartum depression out there than even our national prevalence data are showing," Bastain said.

"Another important implication of our work is that depression can persist long beyond the first 12 months postpartum, and mothers should talk to their healthcare providers if they continue to have symptoms of depression," Bastain added.

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