Fallout – How to reach A bigger number of dwellers

In addition to what's already been mentioned, it is possible to be both pregnant and working in the radio studio. Other comparisons:

• Pregnant women cannot defend against fire, radroaches, or raiders, so if you have 50% of your vault pregnant, you are very vulnerable.
• Children consume resources while they are growing up without contributing to the vault. Having fourteen kids around will drain you dry. Dwellers attracted by the radio are ready to work as soon as they arrive.
• In true Bethesda style, I don't think children can be killed, which means that a bad raider attack could leave you with a vault of just kids, fun.

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.