tailieunhanh - The Fetal Matrix: Evolution, Development and Disease - part 9

Khi phụ nữ trì hoãn mang thai lâu hơn, nguy cơ vô sinh tăng trưởng. Tương tự như vậy, giảm mạnh mẽ trong số lượng tinh trùng ở nam giới phương Tây tạo ra vô sinh không mong muốn, thậm chí trong nhiều cặp vợ chồng trẻ. Cả hai xu hướng này đã xảy ra tại một thời điểm khi các công nghệ hỗ trợ sinh sản đã được rộng rãi. | 201 Primary prevention As women delay pregnancy longer the risks of infertility grow. Likewise the drastic fall in sperm count in Western males produces unwanted infertility even in many younger couples. Both trends have occurred at a time when assisted reproductive technologies have been broadly available. This has led to a great increase in multiple pregnancies and to the associated maternal constraint. The available data also raise the probability that the abnormal environment of the pre-embryo cultured in vitro may have long-term effects - it is too soon yet to know. While the evidence is still preliminary there are increasing clues that for both mother and father there are factors to consider prior to conception. We have already reviewed the evidence in chapter 6 that inappropriate PARs may have been triggered in this period. There may also be sperm effects as well as the egg effects that we have described in some detail. Exposure of the sperm during spermatogenesis to less than optimal conditions may influence the imprinting status of paternal genes after fertilisation and thus produce epigenetic effects. As we noted in chapter 5 data from Sweden reveal that the risk of Type 2 diabetes in men is determined in part by the diet of their grandfathers in the period before they reached puberty. So the challenge may extend to both parents. We have already described animal experiments that suggest that nutrition around the time of conception has important inductive Only now are the necessarily very complex studies being started in which data on nutritional status at the beginning of human pregnancy are collected and then related to the outcome of This is information we badly need. Such data create a real challenge. It may not be sufficient to focus on nutrition once the woman knows she is pregnant -much may have already happened before then that will have lifelong consequences. If that is the case we then need strategies to address how to .