Birth control, also known as contraception and fertility control, are methods or devices used to prevent pregnancy. Planning, provision and use of birth control is called family planning. Safe sex, such as the use of male or female condoms, can also help prevent sexually transmitted infections. Birth control methods have been used since ancient times, but effective and safe methods only became available in the 20th century. Some cultures deliberately limit access to birth control because they consider it to be morally or politically undesirable.
The most effective methods of birth control are sterilization by means of vasectomy in males (99.85% success rate) and tubal ligation in females (99.5% success rate), intrauterine devices (IUDs) and implantable contraceptives. This is followed by a number of hormonal contraceptives including oral pills, patches, vaginal rings, and injections. Less effective methods include barriers such as condoms, diaphragms and contraceptive sponge and fertility awareness methods. The least effective methods are spermicides and withdrawal by the male before ejaculation. Sterilization, while highly effective, is not usually reversible; all other methods are reversible, most immediately upon stopping them. Emergency contraceptives can prevent pregnancy in the few days after unprotected sex. Some regard sexual abstinence as birth control, but abstinence-only sex education may increase teen pregnancies when offered without contraceptive education.
A prescription (℞) is a health-care programme that governs the plan of care for an individual patient and is implemented by a qualified practitioner. A qualified practitioner might be a physician, dentist, nurse practitioner, pharmacist, psychologist, or other health care providers. Prescriptions may include orders to be performed by a patient, caretaker, nurse, pharmacist, physician, other therapist, or by automated equipment, such as an intravenous infusion pump. Formerly, prescriptions often included detailed instructions regarding compounding of medications but as medications have increasingly become pre-packaged manufactured products, the term "prescription" now usually refers to an order that a pharmacist dispense and that a patient take certain medications. Prescriptions have legal implications, as they may indicate that the prescriber takes responsibility for the clinical care of the patient and in particular for monitoring efficacy and safety. As medical practice has become increasingly complex, the scope of meaning of the term "prescription" has broadened to also include clinical assessments, laboratory tests, and imaging studies relevant to optimizing the safety or efficacy of medical treatment.
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The pharmaceutical sciences are a group of interdisciplinary areas of study concerned with the design, action, delivery, disposition, inorganic, physical, biochemical and analytical biology (anatomy and physiology, biochemistry, cell biology, and molecular biology), epidemiology, statistics, chemometrics, mathematics, physics, and chemical engineering, and applies their principles to the study of drugs.
Menstrual cycle is the cycle of changes that occurs in the uterus and ovary for the purpose of sexual reproduction. It is essential for the production of eggs and for the preparation of the uterus for pregnancy. The menstrual cycle occurs only in fertile female humans and other female primates.
In humans, the length of a menstrual cycle varies greatly among women (ranging from 25 to 35 days), with 28 days designated as the average length. Each cycle can be divided into three phases based on events in the ovary (ovarian cycle) or in the uterus (uterine cycle). The ovarian cycle consists of the follicular phase, ovulation, and luteal phase whereas the uterine cycle is divided into menstruation, proliferative phase, and secretory phase. Both cycles are controlled by the endocrine system and the normal hormonal changes that occur can be interfered with using hormonal contraception to prevent reproduction.