If you think you might be peegnant (3-4 weeks) is it harmful to the baby then for heavy lifting? We…

If you think you might be peegnant (3-4 weeks) is it harmful to the baby then for heavy lifting? We aren't sure if we are and we moved this weekend. I lifted a lot, but haven't felt any different. I was nauseous about 4 am like I have been the last couple of mornings but that's all.