16.6) Methods of birth control in humans
Birth control is controlling the number of children and the time to have them. A couple may use birth control if they are not ready to have a baby yet. There are several types and methods of birth control. Types of birth control are natural, chemical, mechanical and surgical.
- Abstinence method is simple avoiding sexual inter course, this way there is no chance the woman will get pregnant.
- Rhythm method is based on the woman understanding her menstrual cycle (period). The woman must be able to sense and predict the time of ovulation when the egg is in the oviduct waiting to be fertilized, and not have sexual intercourse at that time. The woman can know when it is ovulation time of the cycle by seeing the type of mucus secreted by the cervix and lining of the vagina and a slight rise in body temperature
- Spermicides is a cream that contains a substance that will kill sperms. The cream has to be placed in the woman’s vagina before sexual intercourse so that it kills the sperms that will be ejaculated.
- Contraceptive pill is a pill which contains chemicals that prevent the ovaries releasing an egg to the oviduct (ovulation); there won’t be an egg ready for fertilization. In some cases, the pill has to be taken every single day, if it is forgotten once there is a chance of pregnancy. The pill is very effective, but it is not preferred by some women since it could bring other side effects such as mood swings, weight gain or circulatory diseases like strokes. The pill has to be prescribed by a doctor who performs a check up on the woman in advance.
- Intra-uterine device (IUD) is a small T-shaped plastic and copper device, inserted by a doctor into the wall of the uterus, where it probably prevents implantation of a fertilised ovum. There is a small risk of developing uterine infections.
- Intra-uterine system (IUS) is similar to IUD and also releases the hormone progesterone slowly over a long period of time ( up to 5 years). The hormone prevents ovulation.
- Contraceptive implant is a small plastic tube about 4 cm long, which is inserted under the skin of the upper arm of a woman by a doctor. Once in place it slowly releases the hormone progesterone, preventing pregnancy. It last for about 3 years.
- Contraceptive injection contains progesterone and stays effective for between 8 and 12 weeks. It works by thickening the mucus in the cervix. Stopping sperm reaching an egg. It also thins the lining of the uterus, making it unsuitable for implantation of an embryo.
- Condom is simply a layer of cover worn on the penis to keep semen from entering the woman’s body. It is made of stretchy, impermeable material that won’t allow any substance entering the woman’s body from the man or vise versa. The condom also has a great advantage; it also prevents diseases or bacteria and viruses passing from the man to the woman or vise versa.
- Femidom is a female condom that is worn by the woman instead of the man. It acts like a bag in the vagina in which the penis is inserted and the semen is ejaculated without entering the woman’s body.
- Diaphragm is a small, circular piece of rubber which is fit over the woman’s cervix to prevent sperms from passing through it. It is impermeable and it can be used along with spermicidal cream to ensure that sperms will not pass through the cervix.
- Male sterilisation – vasectomy: the man could have his sperm ducts cut and sealed, in this way the sperms won’t even leave his body.
- Female sterilisation – laparotomy: the woman could have an operation to cut and seal her oviducts to ensure that the egg can’t pass down to the uterus.
The use of hormones in fertility and contraception treatments:
Hormones to improve fertility:
- Failure to produce ova can be treated with fertility drugs.
- These drugs are similar to hormones and act by increasing the levels of FSH and LH.
- Administration of the drug is timed to promote ovulation to coincide with copulation.
Hormones for contraception:
- Oestrogen and progesterone control important events in the menstrual cycle.
- These hormones can be used, singly or in combination, in a range of contraceptive methods.
Artificial insemination (AI):
- If the male is infertile, not enough sperm or sperm not mobile enough, pregnancy may be achieved by AI.
- This involves injecting semen through a tube into the top of the uterus.
In vitro fertilisation:
- ‘’In vitro’ means literally ‘in glass’ (allowed to take place in laboratory glassware).
- Multiple ova caused by fertility drugs are collected by laparoscopy (they are sucked up in a fine tube inserted through the abdominal wall).
- The ova are then mixed with the husband’s seminal fluid and watched under the microscope to see if cell division takes place.
- One or more of the dividing zygotes are then introduced to the woman’s uterus by means of a tube inserted through the cervix.
Social implications of contraception and fertility treatments:
Some religions are against any artificial forms of contraception and actively discourage the use of contraceptives such as the sheath and femidom, However, these are important in the prevention of transmission of STDs in addition to their role as contraceptives.
Fertility treatments such as in vitro fertilization are controversial because of the ‘spare’ embryos that are created and not returned to the uterus. Some people believe that since these embryos are potential human beings, they should not be destroyed or used for research. In some cases the ‘spare’ embryos have been frozen and used later of the first transplant did not work.