Too bad George was wrong, but that doesn't matter. The cool think is the prime number gestation question. I've heard certain insects like cycadas (spelling?) do so in primes. The idea being that perhaps nature selected for these because parasite that attacked them would emerge on a different cycle and so the optimal survial condition is that the two groups emerge at the same time as few times as possible, so a Chineses remainder theorem problem which of course favors survival of groups with gestation lengths whose GCD is small -- thus primes are best.

However, the flaw with humans is that we don't procreate at exactly the same time of year so prime gestation times wouldn't have a survival angle for us.

If it was a prime number, we humans would still find a way to make some neat division of the gestation cycle. Let's say 7 months: that would be 28 weeks, which we could then divide into four phases of seven weeks each, or 210 days, which we could divide in three phases of 70 days each (little more than two months). Or say 11 months: that would be about 330 days, which we could divide in three phases of 110 days each (almost four months).

Regardless, there would come a time when the fetus looked so much like a human only the staunchest pro-choicers would still support abortion at that point.