pregnant sows dan't want give birth (generation 3) - march until july

[RobinHood]

I started breeding pigs very early (no farm mod), I was lucky. One day there were pigs at my base, which I fenced in and fed. Pig breeding was quite abundant up to generation 2.

But now I have 2 generation 2 sows, they have had the status of pregnant since March, and now it's July and they are still pregnant, and they don't givte me any birth.

Food they have enough.

[RobinHood]

I got now births, but it took very long