Farmgirl's right I reckon - with all that relaxin in your body, the risk is that you'll injure yourself.

You're much more likely to pull a tummy muscle - I did in early pregnancy this time (my relaxin got a bit excited, I've been very loose this pregnancy!) just by lifting a wet washing basket! And while it sounds like nothing, every time I sneeze, yawn or breathe too deeply I get a twinge. And the muscles struggle to repair themselves, since they're being stretched. Totally not worth it.

Some people say don't lift hardly anything, for me, who usually ignores those things cos I'm 'tough' - I'd say don't try to be tough, be very sensible. Keep a check on yourself, and if it's something that requires your tummy muscles, perhaps give it a miss. I've learned to lift my toddler using my arms and legs, but to be honest, even they don't support me like they used to.

Basically the moral of my rambly story is - if you can get someone else to lift it for you - then do that! (and don't feel like you're being precious - you'll be much more precious with a pulled muscle!)
Otherwise, just be cautious and sensible, be aware that your joints will give out on you MUCH more easily these days.