The Open Door Web Site
Powerpoint Presentation: Human Reproduction
Animal Physiology Index
Sterilization of the female
Several techniques are used all usually irreversible.
Hysterectomy: the total removal of the uterus; Laparotomy the ligation (tying) of the fallopian tubes, entry into the abdomen by a small incision. Alternatively, entry by endoscope through the navel or vagina. The woman could in theory have another child by the implantation of an egg fertilised in vitro (test-tube baby). No change in menstrual cycle.
Sterilization of the male
Vasectomy, the cutting of the vas deferens, which is an irreversible operation. The sperm duct must be cleared of spermatozoa, this can take up to 6 months. Spermatozoa could be stored in liquid nitrogen for future artificial insemination. No change in ejaculation or hormone levels.
Sterilisation is usually only prescribed for a parent of established families (i.e. with children already) or where there is a risk to the mother's health in subsequent pregnancies or if the parent is a carrier of a genetic disease.
The Birth Control Pill
This works on the basis that FSH is inhibited by oestrogen during pregnancy thus preventing further ovulation. Synthetic oestrogens and progestins are present in the pill which is taken daily for a three week period. The dose is stopped for one week to allow a menstrual bleed. Thus the ovaries are permanently inhibited from ovulating.
Side effects include: Blood clots, hypertension, cancer risk, diabetes, nervous depression, nausea (usually for the first 2 months), fatigue, vaginal discharge, weight gain, a more regular menstrual cycle and a disappearance of menstrual cramps. These vary considerably with. the woman. All women who take the pill are advised to consult their doctor regularly and to have a blood and cervical smear test at least once a year.
The mini pill
Progesterone only in a low dose. This tries to reduce the risk of side effects. Its contraceptive effectiveness is reduced dramatically if one pill is forgotten or in periods of illness where the bodies metabolism is elevated (e.g. fever). The mini pill is usually taken continuously without interruption.
DEPO-PROVERA (Depot Medroxyprogesterone acetate). A long lasting birth control method. Injections every 3 to 6 months.
Side effects: Disruption of menstrual bleeding, possible association with cervical cancer and other effects similar to oral contraception.
The morning after pill
These have existed for many decades but recently the introduction of mifepristone (RU486) has made the treatment much safer. Taken under medical supervision within 4 weeks of unprotected sex, it can be used to block a pregnancy and precipitate a miscarriage by inhibiting the progesterone receptors of the uterus. The lining of the uterus loosens and a menstrual bleed starts with the loss of the implanted embryo.
Side effects: Some nausea, headache, weakness, diarrhoea and/or fatigue. Uterine infections are possible. It is not a treatment recommended for heavy smokers or women with high blood pressure.
Intrauterine Device (IUD), Coil or Loop
A plastic or metal device inserted into (and removed from) the uterus by an expert. Mode of operation not certain. It is possible that it irritates the endometrium triggering prostaglandin release causing uterine contractions and preventing implantation. Usually prescribed to women who have already had one child.
Side effects: Injury to the uterus, excessive menstrual bleeding, possible sterility.
Diaphragm or Cap with Spermicidal Jelly or Cream
Various sizes used to fit over the cervix.
Disadvantages: it takes practice to insert properly, it requires a certain amount of premeditation and preparation. The cap needs to be checked once a year.
Side effects: None, though irritation and allergies to the spermicide may cause problems.
Condom or Sheath
Very effective if used properly and nearly 100% effective if used with creams or foams. Placed over the erect penis well before intercourse. After intercourse removal of the condom should be carried out with care.
Side effects: None though lubricants may cause allergies.
A physical and chemical barrier applied in front of the cervix. Not so effective on its own but very effective when combined with a condom or a diaphragm.
Disadvantages: Must be applied just before intercourse.
Side effects: None though it may cause irritation or allergies.
Being aware of her menstrual cycle a woman can to a certain degree predict when ovulation takes place. Use of indicators such as the menstrual bleed, the cervical mucus which changes in texture or body temperature which dips slightly just before ovulation and rises after it. The "safe period" being at least 3 days before ovulation (sperm can live in the uterus/vagina for up to 3 days) and. 36 hours after it (the egg lives for 36 hours but is receptive for about 24h).
Disadvantages: Some women have very variable cycles. Some women are reflex ovulators, ovulating after sexual intercourse no matter what stage of the cycle.
Withdrawal or Coitus Interuptus
Removal of the penis from the vagina just before ejaculation of the semen. Not very effective. Can lead to nervous tension and. disruption of the relationship.
Prolactin, the milk secretion hormone, produced. by the pituitary after birth inhibits FSH and therefore ovulation. However, it only works effectively if the baby is fed milk when it wants it. Any attempt to train the baby into a socially acceptable daily feeding rhythm appears to upset the contraceptive value of breast feeding. Pre-weaning or bottle feeding the baby will also reduce the level of prolactin sooner.
* Reference: R.V. Short (1984) Breast Feeding. Scientific American April p.23.
A lot of mythical methods have developed. including douching (squirting a liquid into the vagina after intercourse), sperms swim too fast; dislodging the sperm by standing up, holding your breath, jumping up and. down after intercourse; not allowing the penis to completely penetrate the vagina - they do not work.
In Vitro Fertilisation (IVF)
The fertilisation of an oocyte by a sperm from a male and a female donor outside the woman, with the subsequent implantation of the early embryo into a receptive female's uterus.
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