Mid-pregnancy pollution exposure linked to postpartum depression

&gt;exposures to mid-pregnancy ambient NO2 and PM10 were associated with nearly four-fold cumulative increased risk of persistent depression<p>I don&#x27;t have access to the full paper, but Im very curious what kind of controls were utilized for this study. Granted, a specific mid pregnancy expsoure causing a 4 fold increase seems significant enough to be able to assign some causation. But some sneaky confounding factors are fun to puzzle on.<p>Maybe poorer mothers (also correlated with depression) have to work longer hours&#x2F;multiple jobs (also correlated) in more heavily polluted environments. But that still wouldnt explain the effect only appearing mid pregnancy...<p>Regardless, I&#x27;m interested to see what the health of humanity looks like in the coming decades. Microplastics in the brain, smog in the lungs, heavy metals in the water, screens in front of our eyes all day. Fun times we live in

Is it clear to anyone else whether the pollution exposure changed during the pregnancy, or whether they’re only talking about the second trimester because it’s the only one that shows statistical significance or something else altogether?