I am not sure about just weight training. I do know that my friend who just had her baby stayed in great shape by doing yoga specially for pregnant women. She also walked 4 miles a day and snow shoed and anything else to stay active that wouldn't put strain on the fetus. She had a healthy weigt gain for the baby, yet was back to her pre baby weight almost immediatley. I personally would am ttc and plan on staying active and using light weights with more repetetion, but with absolutley no strain to the fetus....and definitley the yoga eventhough I don't do that now. good luck to you and sorry for your first loss. we are ttc and it is so frustrating waiting month after month hugh!! i just keep staying in shape and waiting!