I’d go ahead and say the cause is likely related to BPA/BPS compounds in plastics. And the exposure of pregnant women to those compounds.
But ya know, that’s just me.
Edit: lol at downvotes, this is newish research. A lot of new information has landed literally in the last week. I sincerely advise keeping an eye on it as research ramps up.
I’ve posted a couple of papers below, one old, one new. As well as a link to an article that does a good job of summarising where our understanding is currently at.