Humans engage in sexual relations for a variety of reasons other than to produce children. Sexually active couples can use methods of fertility (birth) control to reduce the likelihood of an unintended pregnancy. Since no fertility control method is perfect, couples must weigh the benefits and disadvantages of the various methods. A major consideration is a method's Choose...percentage effectivenessactual failure ratetypical failure ratecost-benefit analysis, which is a measure of how it performs in common use. Two activities that are ineffective for fertility control are Choose...penile withdrawal;douchingdouching; IUDcalendar rhythm; penile withdrawalIUD; caldendar rhythm. Hormonal contraceptives (pills, "shots," implants, patches), which are very effective when used as directed, contain Choose...estrogen onlyeither estrogen only or progestin onlyeither estrogen and progestin or progestin onlyprogestin only. The IUD is a small plastic device that Choose...covers the inner part of the vaginablocks the cervixis placed in the uterusinactivates the ovary. Barrier methods involve blocking the union of sperm and egg with a mechanical (usually rubber) device and/or a sperm-killing chemical. The barrier method used by males is the condom. A common error when using the condom is Choose...putting on the condom prior to ejaculation rather than before sexual activity beginsleaving space at the tiplubricating the condom holding on to the condom when it is being withdrawn. Fertility awareness methods attempt to determine when a woman has produced a fertilizable egg. Choose...calendar rhythmmucus methodtemperature methodchemical method relies on tracking the length of a woman's menstrual cycle. Other methods rely on monitoring hormone-based changes in a woman's physiology. Permanent birth control (sterilization) in the man is called Choose...episiotomytubal ligationvasectomylaparoscopy; it blocks the exit of sperm out of the body. When choosing a method of birth control, the most important thing a couple can do is Choose...consider the typical failure ratediscuss their opinions and concerns so the chosen method will be used correctly and every timeconsider the health dangers of the various methodsfocus on methods for the woman since it is she who can become unintentionally pregnant.. Among the reasons sexually active people do not use birth control are low motivation, lack of knowledge about birth control, negative attitudes about fertility control, and relationship issues; the most effective contraceptors are Choose...individuals not in committed relationshipsindividuals in committed relationshipsindividuals in committed, long-distance relationshipsindividuals who engage in one night stands. Emergency contraception, which Choose...takes place in a hospital emergency roominvolves the D and C techniqueinvolves large doses of estrogenlocks the release of the hormone of pregnancy, hCG, is available in instances when an episode of unprotected intercourse could result in an unintended pregnancy. Abortion is the intentional, premature termination of a pregnancy.