This is an ancient, yet simple, question. Though at conception, the spirit (of its own free will) enters the physical universe in a state of perfection, it is then subject to the physical world. For nine months, it is not only subjected to the recombination of DNA from the parents, it is also subjected to the direct flaws of its mother’s life style. Natural miscarriages are a choice of the spirit (a rejection of the physical universe found within the mother’s womb). Whereas, forced miscarriages are a rejection of the spirit by the mother (a difficult sin to overcome). We are all one in Christ, yet the “sins of the parents are passed on,” not because God is at fault (he has warned and instructed us from the very begining) but because we (collectively) have made poor decisions. If everyone followed the laws given to Moses, the world would be a wonderful and happy place. God does not need rules, and these rules are not to hinder and restrict humanity. Rather, they are given as instruction for lost souls who needed guidance. God does not harm the innocent. As a species, we do the harm, and we must bear the responsibility. Having been given dominion in the physical world, we must use it wisely.