Contraception

Ooh, yay, another post in which I get to show off just how immature I can be! :P

So... contraception. Not to be confused with conception. Conception basically refers to fertilisation, whereas contraception refers to preventing fertilisation from occurring (contra = against). There are many different methods of contraception:

• The rhythm method, the temperature method, the mucus method and the symptothermal method are about determining "safe" days during the woman's menstrual cycle.
• Coitus interruptus involves the withdrawal of the penis before ejaculation occurs.
• Mechanical barriers, such as condoms, diaphragms (not to be confused with the diaphragm in the respiratory system), cervical caps and so on.
• Chemical methods use chemicals to immobilise sperm or prevent them from entering the vagina.
• Hormonal contraceptives are medicines that stimulate the production of certain hormones, which in turn suppress ovulation.
• Intrauterine devices, or IUDs, are small plastic or metal devices that are inserted into the uterus to prevent pregnancy.
• Sterilisation operations are a permanent form of birth control.

Let's have a closer look at all of these. Note: I'm just going to tell you what they are, not when you should use them or anything like that. None of this is to be taken as medical advice. Also, bear in mind that I'm talking mainly about preventing pregnancy- not all of these methods will protect you from STDs.

Ovulation Detection Methods

The rhythm method, the temperature method, the mucus method and the symptothermal method are ways of determining when ovulation has occurred so that the woman can avoid having sex on those days. These methods are not considered particularly reliable, and require the woman to keep careful records. Nevertheless, let's have a look at each method:

• The rhythm method is based on the fact that an egg is released on around day 14 of a 28-day menstrual cycle, and is only available for fertilisation for a few days. Since sperm can linger for a few days, "unsafe days" are generally considered to be between days 10-17 or so. This is the least reliable method, as every woman is different, and even in women with 28-day cycles, not all release eggs on the 14th day.
• The temperature method uses body temperature to determine ovulation. At around the time of ovulation, the woman's body temperature drops before sharply rising (not to the point of a fever- just like 0.5 degrees more or so. Hence a thermometer is needed for this method). It is safe to have intercourse (as in, less likely to have a baby, not less likely to have an STD) 3 days after the temperature rises.
• The mucus method relies on observing changes in the mucus of the cervix. As the time for ovulation approaches, mucus can be detected. It is initially cloudy and sticky, but becomes clearer and more slippery. After ovulation, mucus becomes cloudy again. Intercourse is safe when there is no mucus and more than 3 days after the last day of the clear mucus.
• The symptothermal method uses a combination of the above methods.

Coitus Interruptus

Cotius interruptus is one of the oldest forms of contraception, and is extremely unreliable. It relies on the man recognising the sensations that occur before ejaculation, so that he can remove his penis in time, preventing any sperm from reaching the egg.

Mechanical Barriers

There are several kinds of mechanical barriers. The type that you are probably most familiar with is the condom, which is rolled onto the man's penis. There's also a female condom too, called the Femidom, which lines the vagina. Both of these protect against STDs as well as prevent pregnancy. Other mechanical barriers include the diaphragm, which is a thin rubber cap that fits across the top of the vagina, and the cervical cap, which fits directly over the cervix. The correct size has to be prescribed by a doctor, and the diaphragm or cervical cap has to remain in position for 6 hours after ejaculation.

Chemical Methods

Chemical methods are highly unreliable, but they can complement other forms of contraception. They come in several forms, including creams, tablets and aerosol foam. They contain a spermicide, which immobilises sperm, and react with moisture in the vagina to form bubbles of carbon dioxide gas, which form a barrier, preventing the sperm from entering the vagina.

Hormonal Contraceptives

Hormonal contraceptives are fairly effective. The most well-known is probably "the Pill," which comes in two different varieties- I'll get to them later. There are also injectable contraceptives as well as the "morning-after pill." I don't think there's a version of "the Pill" for males yet, but they're working on one.

The first type of "the Pill" contains substances similar to oestrogen and progesterone. The increased levels of these hormones suppresses the release of pituitary hormones, which in turn prevents ovulation from occurring. The substitute hormones also alter the lining of the uterus so that it is less susceptible to implantation by the fertilised egg. The cervical mucus is also affected- it becomes thick and sticky, which makes it harder for sperm to move through the vagina. This type needs to be taken every day- hormone levels will drop if missed for more than 2 days in a row.

The second type only contains a substitute for progesterone, called progestagen. This type, like the first type, inhibits pituitary hormones, alters the endometrium of the uterus and alters the secretions of the cervix so that the sperm have difficulty travelling to the egg. As it contains no oestrogen, which is responsible for many of the side-effects of the previous type, this type of pill has fewer side-effects. There are also more ways that this type can be taken: pill, injection, capsules that can be implanted into the upper arm, in a vaginal ring and in IUDs (intrauterine devices). Let's have a quick look at these:

The pill form can increase the flow of milk in some lactating women, but it may disturb the menstrual cycle. The progestagen-only pill is also considered the least effective form of hormonal contraception. The injection form may be considered to be more convenient, but menstruation may cease after 6 months. Ovulation and menstruation may continue to be delayed for 9-12 months after the last injection. The capsule implant form provides contraception for 5 years and can be removed at any time, but it also causes long-term suppression of menstruation. The vaginal ring form, placed at the top of the vagina, can be left in place for 3 months or removed at any time. There are some versions of the vaginal ring form that also release low doses of oestrogen. Finally, some IUDs release progestagen. These can be left in place for up to 5 years at a time.

The morning-after pill is a different kind of pill that utilises hormones. Actually, it's made up of several pills, which are taken at different times after intercourse. The morning-after pill either delays ovulation until all sperm have died, or prevents a fertilised egg from implanting in the uterus.

Overall, these hormonal methods are reasonably safe and effective. However, that's not to say that they're without side effects: side-effects include acne, blood clots, increase in blood pressure, headaches, weight gain, nausea, and so on. The risk of some of these side-effects, such as blood clots, increases with age. Certain factors, such as smoking, may also increase your risk of experiencing side-effects.

Intrauterine Devices

Intrauterine devices, or IUDs, are plastic or metal devices inserted into the uterus. They work by damaging and killing sperm, as well as affecting the uterine lining in such a way that the fertilised egg becomes unable to implant there. Some IUDs release hormones (see the section above on "hormonal contraceptives"), while some contain copper, which kills sperm. (See http://www.webmd.com/sex/birth-control/intrauterine-device-iud-for-birth-control for more info.)

Sterilisation

Sterilisation is a permanent form of contraception. There are different forms of sterilisation:

• Vasectomy (men)- a small piece of each vas deferens is removed and the cut ends are tied. Can be done under local or general anaesthetic. Another method includes using high frequency ultrasound to kill the cells in the walls of the vas deferens, causing dead cells to coagulate and form an obstruction in the tube.
• Tubal ligation (women)- a small piece of each uterine tube is removed and the cut ends are tied.

Sterilisation should not be confused with the removal of the gonads (although removing the gonads does cause sterility). Removing the testes, ovaries or uterus are generally only done when the organs are diseased, as removal causes a change in the balance of reproductive hormones, which in turn affects sexual drive and body characteristics. Removal of the testes is castration, removal of ovaries is oophorectomy and removal of the uterus is hysterectomy.

Abortion

If the above methods have failed, an induced abortion may be performed. This is usually done by stretching the cervix and scraping or sucking out the contents of the uterus through the vagina. There are many ethical questions surrounding abortion- I'm not going to go into them here.

Next up: Infertility and reproductive technology!