UK GCSE level age ~14-16, ~US grades 9-10 Biology revision notes re-edit 19/05/2023 [SEARCH]

 Human sexual reproduction: 5. Non-hormonal methods of preventing pregnancy

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(5) Non-hormonal methods of preventing pregnancy

Barrier methods to stop the sperm ever meeting an egg, hence stop fertilisation of egg and therefore no pregnancy.

All such devices must be carefully fitted in place before sexual intercourse takes place.

(i) Condoms made of thin latex are worn over the penis during intercourse to stop sperm entering the vagina.

Female condoms are worn inside the vagina.

Note that male condoms is the best form of contraception that protect you against sexually transmitted diseases, not 100% effective, but many other contraception methods do not protect against STDs at all.

(ii) A diaphragm is a shallow flexible plastic cup or dome shaped device that fits over the opening of cervix making a barrier to the entrance to the uterus.

The diaphragm prevents sperm reaching an egg and it can be used in conjunction with a spermicide that kills sperm.

(iii) A femidom is female condom are made from soft, thin synthetic latex or latex.

The femidom is worn inside the vagina to prevent semen getting to the womb and must be put in place before sexual intercourse.


Killing the sperm

(i) It is possible to use a spermicide on its own as a contraceptive, but is only 70-80% effective, much less than the other contraception methods previously described.

(ii) Copper IUDs (intrauterine device) that kill sperm and prevent them surviving in the uterus, and so can never fertilise a released egg (non-hormonal method).


Sterilisation - requires a surgical procedure

This involves cutting or tying tubes in the reproductive system ...

(i) female (female sterilisation) - the fallopian tubes (oviducts) which connect the ovaries to the uterus, are cut, sealed or blocked by an operation so that eggs cannot be released into the uterus.

(ii) male (male vasectomy) - the sperm duct tube that connects the testes with the penis is cut, sealed or tied so that sperm cannot be mixed with semen and injected into the vagina in sexual intercourse.

These are surgical procedures with a permanent effect -there is only a very small chance of the tubes joining up again.

Successful surgery is nearly 100% effective, and very difficult to reverse.


'Natural' methods of family planning, unprotected sex and the menstrual cycle

This involves knowing when the woman is most fertile within the 28 day menstrual cycle.

Therefore the idea is to avoid sexual intercourse during these fertile periods.

At around 14 days when the egg is released (ovulation) there is a slight increase in temperature.

By estimating when ovulation might occur, by avoiding sexual intercourse at that time, you reduce the chance of fertilising an egg.

However, it is not very effective, because eggs and sperm can live for several days and a woman's cycle can be irregular, but it is used by people who think that barrier and hormonal methods are unnatural (or considered ethically wrong by some religious teachings).

The cervical mucus method is a way to identify fertile times to help you gauge the best days to have or avoid unprotected sex and require careful observation of mucus patterns in the menstrual cycle.

Before ovulation, cervical secretions change creating a situation that helps sperm travel through the cervix, uterus and fallopian tubes to the egg.

By recognizing changes in the cervical mucus, the woman can try to pinpoint when you're most likely to ovulate, hence most likely to conceive.

If the woman is hoping to get pregnant, she can use the cervical mucus method to determine the best days to have sex.

Conversely, if the woman wants to avoid pregnancy, the cervical mucus method can help predict which days to avoid having unprotected sex..

The man can also remove his penis before ejaculation to prevent sperm entering the uterus, but that requires a good deal of self control.


Abstinence period

No sexual intercourse at all, is the only truly 100% guaranteed pregnancy prevention!



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