... is unlikely to have harmed a baby, as long as the mum isn't drinking at very high levels, and as long as she stops drinking when she knows she's pregnant.
What's got me thinking about this was listening to a true crime podcast where they had a paediatrician talking about fatal alcohol syndrome, and that made me reflect on a thread I read on here a few weeks ago.
On the thread a few weeks ago a poster said that she hadn't discovered her pregnancy until she was 3 months+ (I think) and that she'd drunk quite a lot before knowing. Most of the rest of the posters reassured her that they had also drunk during early pregnancy and that their children were fine. One poster said her obstetrician had said he'd only seen one case of FAS in his career and that it was very rare.
My understanding of FAS is that it's a spectrum disorder, and that children's development can be negatively affected at lower levels of consumption, and that fetal alcohol spectrum disorders can be quite difficult to diagnose because a child can have sustained developmental damage without having the typical features of FAS (short nose, small eye sockets, flat filtrum).
I know if I'd been drinking in pregnancy I'd want to be told it didn't matter, but then I worry that the message that only heavy drinking may harm a baby, and that if the baby is harmed it's always obvious, isn't necessarily a good one to have out there in a culture where heavy drinking among young women is pretty prevalent. Apparently FASD is often misdiagnosed as in older children or adults as ADHD or ASD.
I'm saying all this by the way as someone who didn't stop drinking during any of my pregnancies, though I always drank at a very low level (i.e., 1 or 2 units once or twice a week, as OK'd by my GP at the time). If I'd known then what I know now I don't think I would have drunk at all.