I asked my Obstetrician about lifting things during my son's pregnancy as I was a surgical vet nurse at the time and often carried unconscious dogs of all sizes from theatre to recovery after surgery (or at least lifted them from the stretcher to their bed). He said that the risk is not to the baby, but to the Mum. Because of the relaxin in your body it's much easier to "pull" muscles and hurt yourself than before you were pregnant. If you have no other pregnancy complications it's just a good idea to be aware of what you are lifting and lift things in the safest manner, and also remember that it's more than ok to ask for help when pregnant

I have severely separated abdominal muscles and also pelvic instability so my Ob prefers me to avoid lifting basically anything, lol. But he also understands that I have a 12 month old that I carry a lot, and also a 2yr8mth old that sometimes needs picking up. Yes, it makes things worst for me and can flare up my pelvic instability, but us Mummies are tough hehe.