silver entirely down to you - after all you know yours better than anyone (and the risks even with the steadiest horse).
I've been riding since a toddler and although I stopped competing in my early 20s, I carried on when I could with a shared ponee. I stopped at 3 months with LC, partly because I kept wetting the saddle () and partly because she was a VERY high strung TB ex racehorse and I couldn't stay mentally ahead of her when I became too protective of myself/baby. I have done virtually no riding since as have a) didn't have time with new baby and noone to help share childcare, b) wetting saddle problems continued and c) moved away after a couple of years, just when I was ready to "get back in the saddle" so had no access to ponee. My parents do driving trials so I've been able to at least smell the muck when I need a fix. Was literally going to go to the stables to ask about lessons/hacking options etc when I got my BFP (remember ski?).
So I'm very of yous who have your own, although not of the work involved! I find it hard enough to keep the dog walked...
My friend rode hers until about 8 months, including falling off at a gallop at 7 months ("don't EVER tell my mum!"). She has a gorgeous 18 month old. There's a risk, but there's many things which are riskier.
Personally, in your shoes (and those of you with poniez) I would ride as much as poss now as after the baby comes it's often much harder, even with a supportive partner, and impossible, pretty much, without.