Why do babies come in groups?

Do they get inspired by other babies that have made it through recently, and decide to come early just to join in the fun? It's a funny image, but it kept coming to me recently as seven babies came in a steady stream. The due dates ranged from August 28th to October 14th...but they all decided to come in a 10 day period. 

But let's just recap the past 6 months...
Of the births that I attended, there were:
32 beautiful babies
31 labours (yes, there was a set of twins in there)
30 vaginal births (yes, just one cesarean - 3.1%...not the twins!)
23 (74%) totally undisturbed births (i.e. just go into labour, have someone listen to baby, rare vaginal exams at the mother's request, and that's all)
4 epidurals (that includes the cesarean)

As each woman's birth story became reality, I would tell my other clients, hoping to inspire confidence.

These stories seemed to have a cumulative effect...with amazing results.

We are all in awe.