But there is a lot you can do before that, to increase the chance of having a healthy pregnancy and a healthy baby, when the time is right. It can also affect his sex drive libido. Testes need to be a few degrees cooler than the rest of the body to make good quality sperm. If it gets too hot around the testes, they can have problems making sperm. Testes will start producing sperm again once the temperature of the scrotum stays at its normal lower level, which might take a few months.