Does lsd cause birth defects?

Controversial. But the overall tide of opinion is that the answer is "no." there was laboratory evidence that lsd could cause damage to germ cells - sperm and eggs - even long after it's ingestion. However, studies of this have not yielded consistent results. There are no human studies, and the vast majority of lsd users (esp in pregnancy) use other substances as well. Avoiding any drugs in pregnancy is best.