Why don't my female dwellers give birth to children?

Solution 1:

Do you have many dead people in your vault?

Due to the fact, that a dead dweller can be revived even 24 hours after his dead, you cannot get above the limit with a new born child.

Just an example of that what I mean:

• Your vault maximum is 38 dwellers.
• You have 30 alive dwellers, 8 dead dwellers and 2 pregnant dwellers
• If the birth would happen, you would have 32 alive dwellers (of which are 0 pregnant and 2 children). You would have 6 dwellers left to your maximum capacity.
• If you would revive all of the 8 dead dwellers, you would have 40 out of 38 allowed dwellers.

Maybe this gives you a hint and maybe this is your case too.

The idea of the dead father won't work. I have also some new born which had a dead father. The icon of the father was just a grave, but it was found. The birth take place and everything else was normal. But well, it still could be a rare bug.

Solution 2:

Its probably because the father of the unborn baby is dead.

When the baby becomes born, the father cannot be found to be listed, so the game doesn't progress to prevent a crash.