OP I can totally sympathise. My upstairs neighbour engaged in a campaign of what I can only describe as harassment over about an 18 month period which involved constant complaints about the smallest things: shutting my door too loudly, using my hair-dryer after 10.30pm, stray empty bin bags in her recycling bin.
Eventually she upped her game and claimed that a plumbing problem was caused by me and was a result of my "faulty assets". It turned out to be nothing of the sort.
I tried to accommodate her initially where possible but as her demands became more and more unreasonable I eventually just started ignoring her at which point she completely lost the plot, threatened to sue me, reported me to environmental health (who told her she was batshit and to back the fuck off).
There are people like this everywhere. Small minded, negative, anal retentive people who don't have enough to worry about in their own lives get a kick out of bullying other people for not falling into line with their every demand.
After a while you learn to ignore, smile sweetly, reflect that you will always be a million times happier than them and thank the Lord that you don't have a rod up your ass.
Best of luck with your pregnancy.