I used to think pregnant women rubbed their bellies all the time because they wanted to hurt me. And I'm not entirely ready to give up on that hypothesis. It seems so reasonable. But since I've taken it upon myself to do some research on this whole pregnancy deal (no need to thank me--I live to serve) other possibilities are beginning to seem viable.
1. To provide data for proprioceptive adjustments. A couple of times I've gotten stuck by attempting to go places I no longer fit, and my Bun Bump is still small. But I've had about 20 years of being a particular shape, and my brain hasn't figured out yet that things are different. Giving my somatosensory cortex constant input about my changing dimensions helps.
2. To maximize the experience of fetal movement. It's still not enough for me to feel Bun Bun from the inside, I want to feel him from both the inside and the outside simultaneously. Which means Constant! Vigilance! is required.
3. And, okay, FINE, an overwhelming sense of love and protectiveness. Although I know that when I lovingly rub my belly I'm just rubbing myself--which is quite foolish when you get down to it--it's as close as I can get to hugging my little one, and it just seems to happen without my really intending it. The tender stroking simply flows out of me. In the grocery store this weekend Mr. Bunny found me standing in the produce section tenderly stroking a pear.
So the next time you see a mooney pregnant lady groping herself, just be aware that while she's probably doing it because she knows you're struggling with family-building and she wants you to suffer, she might have some other, secondary reasons.