Can exposure to THC affect embryos? It seems really likely, but it also seems like the science isn't entirely clear

Available studies on marijuana exposure in pregnancy were reviewed and support some degree of developmental disruption, including an increased risk of fetal growth restriction and adverse neurodevelopmental consequences. However, much of the existing prenatal marijuana research was performed in the 1980s, when quantities of THC were lower and the frequency of use was less. Additionally, most human studies are also limited and conflicting as most studies have been observational or retrospective, relying primarily on patient self-report and confounded by polysubstance abuse and small sample sizes, precluding determination of a causal effect specific for marijuana. Given the paucity of evidence, it is currently recommended to avoid using marijuana while pregnant or when breastfeeding.

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Idk, I'm not a doctor and I haven't done a ton of reading on this. I want children to grow up healthy, and part of that is preventing them from being exposed to chemicals that will mess up their development, but another important part of that is not throwing their parents in jail or prison unless it's absolutely necessary, so idk how I feel about this.

Do they currently prosecute women for drinking while pregnant or is this just a "reefer bad" thing?

I am absolutely pro choice.
But I agree that drugs during pregnancy (weed, booze, anything that might harm the future child) should be prevented.
Which, I feel, puts me in an odd spot by my apparent hypocritical application of "My body, my choice".

So, I think it is to do with the intention.
If someone intends to carry a baby to full term, then they should be responsible for ensuring that future child's well being.
If that person makes the choice not to carry the baby to full term, then yeh: their body, their choice. I have no issue with them taking drugs or whatever.