Aug 11, 2010

Birth Control Methods (I)

         The practice of contraception is as old as human existence. For centuries, humans have relied on their imagination to avoid pregnancy. Ancient writings noted on the Kahun papyrus dating to 1850 BCE refer to contraceptive techniques using a vaginal pessary of crocodile dung and fermented dough, which most likely created a hostile environment for sperm. The Kahun papyrus also refers to vaginal plugs of gum, honey, and acacia. During the early second century in Rome, Soranus of Ephesus created a highly acidic concoction of fruits, nuts, and wool that was placed at the cervical os to create a spermicidal barrier.
             Today, the voluntary control of fertility is of paramount importance to modern society. From a global perspective, countries currently face the crisis of rapid population growth that has begun to threaten human survival. At the present rate, the population of the world will double in 40 years; in several of the more socioeconomically disadvantaged countries, populations will double in less than 20 years.
On a smaller scale, effective control of reproduction can be essential to a woman's ability to achieve her individual goals and to contribute to her sense of well-being. A patient's choice of contraceptive method involves factors such as efficacy, safety, noncontraceptive benefits, cost, and personal considerations. This article addresses the predominant modes of contraception used in the United States, along with the safety, efficacy, advantages, disadvantages, and noncontraceptive benefits of each.

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Periodic Abstinence

Coitus Interruptus

Coitus interruptus involves withdrawal of the entire penis from the vagina before ejaculation. Fertilization is prevented by lack of contact between spermatozoa and the ovum. This method of contraception remains a significant means of fertility control in the developing world.
Effectiveness depends largely on the man's capability to withdraw prior to ejaculation. The failure rate is estimated to be approximately 4% in the first year of perfect use. In typical use, the rate is approximately 19% during the first year of use.
Advantages include immediate availability, no devices, no cost, no chemical involvement, and a theoretical reduced risk of transmission of sexually transmitted diseases (STDs).
The probability of pregnancy is high with incorrect or inconsistent use.
Lactational Amenorrhea
Elevated prolactin levels and a reduction of gonadotropin-releasing hormone from the hypothalamus during lactation suppress ovulation. This leads to a reduction in luteinizing hormone (LH) release and inhibition of follicular maturation. The duration of this suppression varies and is influenced by the frequency and duration of breastfeeding and the length of time since birth. Mothers only need to use breastfeeding to be successful; however, as soon as the first menses occurs, she must begin to use another method of birth control to avoid pregnancy.
The perfect-use failure rate within the first 6 months is 0.5%. The typical-use failure rate within the first 6 months is 2%.
Involution of the uterus occurs more rapidly. Menses are suppressed. This method can be used immediately after childbirth. This method facilitates postpartum weight loss.
Return to fertility is uncertain. Frequent breastfeeding may be inconvenient. This method should not be used if the mother has human immunodeficiency virus (HIV) infection.
Natural Family Planning
Natural family planning is one of the most widely used methods of fertility regulation, particularly for those whose religious or cultural beliefs do not permit devices or drugs for contraception. This method involves periodic abstinence, with couples attempting to avoid intercourse during a woman's fertile period, which is around the time of ovulation. Techniques to determine the fertile period include the calendar method, cervical mucus method, or the symptothermal method.
The calendar method is based on 3 assumptions as follows:
(1) A human ovum is capable of fertilization only for approximately 24 hours after ovulation,
(2) spermatozoa can retain their fertilizing ability for only 48 hours after coitus, and
(3) ovulation usually occurs 12-16 days before the onset of the subsequent menses. The menses is recorded for 6 cycles to approximate the fertile period. The earliest day of the fertile period is determined by the number of days in the shortest menstrual cycle subtracted by 18. The latest day of the fertile period is calculated by the number of days in the longest cycle subtracted by 11.
With the cervical mucus method, the woman attempts to predict her fertile period by quantifying the cervical mucus with her fingers. Under the influence of estrogen, the mucus increases in quantity and becomes progressively more elastic and copious until a peak day is reached. This is followed by scant and dry mucus, secondary to the influence of progesterone, which remains until the onset of the next menses. Intercourse is allowed 4 days after the maximal cervical mucus until menstruation.
The symptothermal method predicts the first day of abstinence by using either the calendar method or the first day mucus is detected, whichever is noted first. The end of the fertile period is predicted by measuring basal body temperature. The basal body temperature of a woman is relatively low during the follicular phase and rises in the luteal phase of the menstrual cycle in response to the thermogenic effect of progesterone. The rise in temperature can vary from 0.2-0.5°C. The elevated temperatures begin 1-2 days after ovulation and correspond to the rising level of progesterone. Intercourse can resume 3 days after the temperature rise.
The failure rate in typical use is estimated to be approximately 25%.
No adverse effects from hormones occur. This may be the only method acceptable to couples for cultural or religious reasons. Immediate return of fertility occurs with cessation of use.
This is most suitable for women with regular and predictable cycles. Complete abstinence is necessary during the fertile period unless backup contraception is used. This method requires discipline. The method is not effective with improper use. The failure rate is relatively high. This method does not protect against STDs.

       For excellent patient education resources, visit eMedicine's: Men's Health Center and Pregnancy and Reproduction Center.

       Also, see eMedicine's patient education articles Birth Control Overview,

Birth Control Barrier Methods,
How to Use a Condom,
Tubal Sterilization,
Understanding Birth Control Medications (Contraceptives),
Birth Control Hormonal Methods, Birth Control Intrauterine Devices (IUDs)
Emergency Contraception.
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