SexologyChapter 7Contraception and abortionBoth babies and mothers are healthier if pregnancies are spaced three to five years apart. Hormonal methods of contraception are highly effective and come in a number of formsThe pillThe patchThe vaginal ringInjectionsThe combination pill Combination birth control pills: birth control pills that contain a combination of estrogen and pregestin (progesterone), both at higher than natural levels.A women takes the pill for 21 days, and then no pill or a placebo for 7 days, after which she repeats the cycle.Variations have been introduced.How it works The pill works mainly by preventing ovulation.When a women starts taking the birth control pills, estrogen levels are high. This high level of estrogen inhibits FSH production, and the message to ovulate never sends out.The high level of progesterone inhibits LH production, further preventing ovulation.The progestin provides additional backup effectsIt keeps the cervical mucus very thickMaking it difficult for the sperm to get throughIt changes the lining of the uterus in such a way that even if a fertilized egg were to arrive,implantation would be unlikelyWhen the estrogen and progestin are withdrawn, the lining of the uterus disintegrates, and withdrawal bleeding or menstruation occurs.The flow is typically reduced because the progestin has inhibited development of endometrium.Effectiveness Failure rate: the pregnancy rate occurring using a particular method; the...