Scientists have made a breakthrough that could be used to design a new class of contraceptive pills

A sperm's path to an egg is more a deadly obstacle course than a track sprint. The one ejaculated sperm cell in a million that is lucky enough to reach the fallopian tubes, where eggs await fertilization, must conquer thick, gelatinous layers of mucus and cells surrounding the egg to reach its prize. Fortunately for the sperm, there is help. Two studies have shown how sperm sense progesterone, a