The behind the scenes activities that are going on in a woman's body at this time, run on the lines of a train chugging to a halt. The ovaries produce and release eggs erratically, and definitely less regularly. The menstrual cycle, whose main purpose is to carry the eggs to the uterus and then out, also becomes irregular. Likewise, when there are no eggs released, chemicals that may encourage conception will also decrease, thus bringing down fertility.