<p>I kinda worry about this too! My son is 18 months and only 24 lbs, but he loves to sit on my belly and bounce on it like it's a ball <span id="user_yui_3_4_1_22_1321553766532_10"><img alt="lol.gif" id="user_yui_3_4_1_8_1321553766532_151" src="http://files.mothering.com/images/smilies/lol.gif" style="width:15px;height:31px;"></span> He doesn't understand at all, and I try to keep him off, but it's hard! I don't think he could do any damage, but I'm going to ask my midwife next appointment just to check. It does hurt when he bounces but I think that's from the scarring from my c-section. I do that that in general, the fluid around the baby keeps them safe and absorbes most of the impact. <span id="user_yui_3_4_1_22_1321553766532_16"><img alt="thumb.gif" id="user_yui_3_4_1_8_1321553766532_280" src="http://files.mothering.com/images/smilies/thumb.gif" style="width:23px;height:18px;"></span></p>