Without more information, it would be difficult to say exactly what's causing that situation, however it sounds like something we've seen before when people try to make the game go faster. A popular way to speed up game play is to "time-travel" by messing with the computer's system clock. Unfortunately, the real-time engine in Virtual Villagers is very complex and relies on the accuracy of the system clock. If you have adjusted your computer's system clock, there's no telling when they will finish nursing the babies.
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Barbara
Unicorn
Last Day of Work