Birth Control Methods

 [• How do oral contraceptives reduce the likelihood of pregnancy?

• How do some methods of birth control protect against sexually transmitted diseases?

• What is the problem with developing an oral contraceptive pill for males? ]

Surgical Sterilization

Sterilization is a procedure that renders an individual incapable of further reproduction. The principal method for sterilization of males is a vasectomy (va-SEK-toˉ-me¯; -ectomy -

 cut out), in tubes, the tubes can be tied and/or cut, and sometimes they are

cauterized. In any case, the result is that the secondary oocyte cannot pass through the uterine tubes, and sperm cannot reach the oocyte.

Non-incisional Sterilization

Essure® is one means of non-incisional sterilization that is an alternative to tubal ligation. In the Essure procedure, a soft micro-insertcoil made of polyester fibers and metals (nickel–titanium and stainless steel) is inserted with a catheter into the vagina through the uterus, and into each uterine tube. Over a three-month period, the insert stimulates tissue growth (scar tissue)

in and around itself, blocking the uterine tubes. As with tubal ligation, the secondary oocyte cannot pass through the uterine tubes,And sperm cannot reach the oocyte. Unlike tubal ligation, non-incisional sterilization does not require general anesthesia

Hormonal Methods

Aside from complete abstinence or surgical sterilization, hormonal methods are the most effective means of birth control.

Oral contraceptives (the pill) contain hormones designed to prevent pregnancy. Some, called combined oral contraceptives(COCs), contain both progestin (hormone with actions similar to progesterone) and estrogens. The primary action of COCs is to inhibit ovulation by suppressing the gonadotropins FSH and LH.

The low levels of FSH and LH usually prevent the development of a dominant follicle in the ovary. As a result, levels of estrogens do not rise, the midcycle LH surge does not occur, and ovulation

does not take place. Even if ovulation does occur, as it does in some cases, COCs may also block implantation in the uterus and inhibit the transport of ova and sperm in the uterine tubes.

 Progestins thicken cervical mucus and make it more difficult for sperm to enter the uterus. Progestin-only pills thicken cervical mucus and may block implantation in the uterus, but they do not consistently inhibit ovulation.

 Among the noncontraceptive benefits of oral contraceptives are regulation of the length of menstrual cycle and decreased menstrual flow (and therefore decreased risk of anemia). The pill also provides protection against endometrial and ovarian cancers and reduces the risk of endometriosis. However, oral contraceptives may not be advised for women with a history of blood clotting disorders, cerebral blood vessel damage, migraine headaches,

hypertension, liver malfunction, or heart disease. Women who take the pill and smoke face far higher odds of having a heart attack or stroke than do nonsmoking pill users. Smokers should quit smoking or use an alternative method of birth control.

Following are several variations of oral hormonal methods of

contraception:

• Combined pill. The combined pill contains both progestin and estrogens and is typically taken once a day for 3 weeks to prevent pregnancy and regulate the menstrual cycle. The pills taken during the fourth week are inactive (do not contain hormones)

and permit menstruation to occur. An example is Yasmin.

• Extended cycle birth control pill. Containing both progestin and estrogens, the extended cycle birth control pill is taken once a day in 3-month cycles of 12 weeks of hormone-containing pills followed by 1 week of inactive pills. Menstruation occurs

during the thirteenth week. An example is Seasonale®.

• Minipill. The minipill contains low dose progestin only and is taken every day of the month. An example is Micronar.Non-oral hormonal methods of contraception are also available.

Among these are the following:

• Contraceptive skin patch. The contraceptive skin patch

(Ortho Evra®) contains both progestin and estrogens delivered in a skin patch placed on the upper outer arm, back, lower abdomen, or buttocks once a week for 3 weeks. After 1 week, the

patch is removed from one location and then a new one is

placed elsewhere. During the fourth week no patch is used.

• Vaginal contraceptive ring. A flexible doughnut-shaped ring

about 5 cm (2 in.) in diameter, the vaginal contraceptive ring

(NuvaRing®) contains estrogens and progesterone and is inserted by the female herself into the vagina. It is left in the vagina for 3 weeks to prevent conception and then removed for

one week to permit menstruation.

• Emergency contraception (EC). Emergency contraception

(EC), also known as the morning-after pill, consists of progestin and estrogens or progestin alone to prevent pregnancy following

unprotected sexual intercourse. The relatively high levels of progestin and estrogens in EC pills provide inhibition of FSH and LH secretion. 

Loss of the stimulating effects of these gonadotropic hormones causes the ovaries to cease secretion of their

own estrogens and progesterone. In turn, declining levels of estrogens and progesterone induce shedding of the uterine lining,thereby blocking implantation. One pill is taken as soon as possible but within 72 hours of unprotected sexual intercourse. The

second pill must be taken 12 hours after the first. The pills work in the same way as regular birth control pills.

• Hormone injections. Hormone injections are injectable pro-

gestins such as Depo-provera® given intramuscularly by a

health-care practitioner once every 3 months.

Intrauterine Devices

An intrauterine device (IUD) is a small object made of plastic,copper, or stainless steel that is inserted by a health-care professional into the cavity of the uterus. IUDs prevent fertilization from taking place by blocking sperm from entering the uterine tubes. The

IUD most commonly used in the United States today is the Copper

T 380A, which is approved for up to 10 years of use and has long-term effectiveness comparable to that of tubal ligation. Some women cannot use IUDs because of expulsion, bleeding, or discomfort.

Spermicides

Various foams, creams, jellies, suppositories, and douches that contain sperm-killing agents, or spermicides (SPER-mi-sı¯ds), make the vagina and cervix unfavorable for sperm survival and are available without prescription. They are placed in the vagina before sexual intercourse. The most widely used spermicide is nonoxynol-9,which kills sperm by disrupting their plasma membranes. A spermicide is more effective when used with a barrier method such as a male condom, vaginal pouch, diaphragm, or cervical cap.

Barrier Methods

Barrier methods use a physical barrier and are designed to prevent sperm from gaining access to the uterine cavity and uterine tubes. In addition to preventing pregnancy, certain barrier methods (male condom and vaginal pouch) may also provide some protection against sexually transmitted diseases (STDs) such as AIDS. In contrast, oral contraceptives and IUDs confer no such

protection. Among the barrier methods are the male condom, vaginal pouch, diaphragm, and cervical cap.

 A male condom is a nonporous, latex covering placed over the penis that prevents deposition of sperm in the female reproductive tract. A vaginal pouch, sometimes called a female condom, is designed to prevent sperm from entering the uterus. It is made of

two flexible rings connected by a polyurethane sheath. One ring

lies inside the sheath and is inserted to fit over the cervix; the other ring remains outside the vagina and covers the female external genitals. A diaphragm is a rubber, dome-shaped structure that fits over the cervix and is used in conjunction with a spermicide. It can be inserted by the female up to 6 hours before intercourse. The diaphragm stops most sperm from passing into the cervix and the

spermicide kills most sperm that do get by. Although diaphragm use does decrease the risk of some STDs, it does not fully protect against HIV infection because the vagina is still exposed. A cervical cap resembles a diaphragm but is smaller and more rigid. It fits

snugly over the cervix and must be fitted by a health-care professional. Spermicides should be used with the cervical cap.

Periodic Abstinence

A couple can use their knowledge of the physiological changes that occur during the female reproductive cycle to decide either to abstain from intercourse on those days when pregnancy is a likely

result, or to plan intercourse on those days if they wish to conceive a child. In females with normal and regular menstrual cycles, these physiological events help to predict the day on which

ovulation is likely to occur.

 The first physiologically based method, developed in the 1930s, is known as the rhythm method. It involves abstaining

from sexual activity on the days that ovulation is likely to occur in each reproductive cycle. During this time (3 days before ovulation, the day of ovulation, and 3 days after ovulation) the couple abstains from intercourse. The effectiveness of the rhythm method

for birth control is poor in many women due to the irregularity of the female reproductive cycle. Another system is the sympto-thermal method (STM), a

natural, fertility-awareness-based method of family planning that is used to either avoid or achieve pregnancy. STM utilizes normally fluctuating physiological markets to determine ovulation such as increased basal body temperature and the production of

abundant, clear, stretchy cervical mucus that resembles uncooked egg white. These indicators, reflecting the hormonal changes that govern female fertility, provide a double-check system by which a female knows when she is or is not fertile. Sexual intercourse

is avoided during the fertile time to avoide pregnancy. STM users

observe and chart these changes and interpret them according to

precise rules.

Abortion

Abortion refers to the premature expulsion of the products of conception from the uterus, usually before the twentieth week of pregnancy. An abortion may be spontaneous (naturally occurring;also called a miscarriage) or induced (intentionally performed).

 There are several types of induced abortions. One involves mifepristone (MIF-pris-toˉn), also known as RU 486. It is a hormone approved only for pregnancies 9 weeks or less when taken

with misoprostol (a prostaglandin).Mifepristone is an antiprogestin; it blocks the action of progesterone by binding to and blocking progesterone receptors. Progesterone prepares the uterine endometrium for implantation and then maintains the uterine lining after implantation. If the level of progesterone falls during preg-

nancy or if the action of the hormone is blocked, menstruation occurs, and the embryo sloughs off along with the uterine lining.Within 12 hours after taking mifepristone, the endometrium starts to degenerate, and within 72 hours it begins to slough off. Misoprostol stimulates uterine contractions and is given after mifepris-

tone to aid in expulsion of the endometrium. Another type of induced abortion is called vacuum aspiration

(suction) and can be performed up to the sixteenth week of pregnancy. A small, flexible tube attached to a vacuum source is inserted into the uterus through the vagina. The embryo or fetus,placenta, and lining of the uterus are then removed by suction. For

pregnancies between 13 and 16 weeks, a technique called dilation and evacuation is commonly used. After the cervix is dilated, suction and forceps are used to remove the fetus, placenta,

and uterine lining. From the sixteenth to twenty-fourth week, a

late-stage abortion may be employed using surgical methods similar to dilation and evacuation or through nonsurgical methods using a saline solution or medications to induce abortion. Labor may be induced by using vaginal suppositories, intravenous infusion, or injections into the amniotic fluid through the uterus.