I went back to it to confirm (I sometimes read while sleep deprived so my judgement falls short lol) and tbh, yeah, he looked like he was full term judging from his belly, but the baby itself looked premature almost, super small with a red hand, like in miscarriages. That's why I thought of a miscarriage, also given the omega's reaction of pure shock. It seemed like a still birth of some sort, especially because the baby itself was covered (usually stories show them), and it just fit in the palm of a hand. But a pregnancy and birth against one's will is also very traumatic and he did it by himself at home, so yeah, maybe it was that and not a stillbirth.

First time seeing an actual miscarriage in omegaverse.