This is a bit of a preemptive Aibu (and my first, so grateful for gentleness).
Our PFB is due any day now. Our neighbours like football and often celebrate/moan loudly during matches, just over what will be the baby's room (don't really have the luxury of using a different room). If this happens during the relatively late night World Cup matches, WIBU to ask them to keep it down? MIL says baby is more likely to be woken by his own movements and needs than any external noise source, so it probably won't be an issue. Would you agree, and alternatively if the noise does bother him (or us), is it ok to have a polite word? If the polite approach doesn't work, what would you do?
By the way, it is highly unlikely that the baby crying will disturb them, because noise travels down not up in our block of flats.