Our first three babies, all girls, each weighed about seven pounds at birth. When our fourth arrived, he was much larger.

After delivery, the medical team began testing and measuring my new son. The last reading came from a nurse, who seemed impressed as she read, "Weight, nine pounds, eight ounces."

My husband, a CPA in corporate finance who'd been quiet up to this point, could contain himself no longer.

"How about that!" my husband exclaimed happily. "It's 36.5% more baby!"