Natural
A woman is at her highest chance of becoming pregnant around the time of ovulation as this is when the egg is released from the ovary. If there are sperm in the vagina, womb or fallopian tubes around this time, there is a chance that the sperm and egg will meet and conception (pregnancy) will occur. Around the time of ovulation, the cervical mucus becomes much more slippery, there is a slight increase in body temperature and the hormone LH (luteinising hormone) increases in the blood and urine. Body temperature and changes in the mucus can be measured daily. Ovulation predictor tests can also be purchased which detect the increase in LH in the urine. Some women choose to monitor these changes so as to predict when she is most and least likely to become pregnant during her cycle. Any women using this method as contraception needs to undertake several months of monitoring to see the natural rhythm of her menstrual cycle. Because of normal variation within and between cycles and mistakes in understanding these changes, natural family planning is only about 75% effective.