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  • History of Oral Contraceptives Post 2

    Posted on August 1st, 2011 Patricia No comments

    The modern-day contraceptive has its roots in the science of endocrinology, which has provided the understanding of the human ovulatory cycle and thus help develop effective contraception. In order to be fertilized, an ovum must first mature while still within its ovarian follicle. Its maturation is prompted by the release of follicle-stimulating hormone from the anterior pituitary gland. The release of this hormone is inhibited when the concentration of the estrogenic hormones, which modulates phases of the menstrual cycle, rises in the blood. Thus modern oral contraceptives inhibit the maturation of the follicles and their ova, so that fertilization can’t occur, by keeping estrogen concentrations in the blood at relatively high levels.

    Estrogenic compounds are thought to be produced by animals only. This assumption was challenged when several plant species were shown to produce estrogenic compounds also. Evidence of how plant substances may affect animal fertility came from sheepherders who noticed that animals that grazed on the clover from the species Trifolium subterraneum sharply reduced fertility in sheep. Although they were effective in one species, they did not produce the same effect in all mammals. Among other plants, the root of Pueraria mirifica used by Thai women to induce abortion also contains an estrogenic compound called miroestrol.

    These estrogenic compounds are steroids. Some of the steroids found in the human body include estrogens (mostly estradiol), testosterone and progesterone. Estrogens can be used to control fertility but they are found in mammals in nanogram (a billionth of a gram) quantities and thus isolating these from animals is not economically feasible. Besides, natural estrogens must be injected to be effective because they are not absorbed when taken orally. Clearly, in order for estrogens to succeed as an oral contraceptive researchers had to find cheaper sources of estrogen derivatives that were effective when taken orally.

    Plants that contained copious amounts of steroids were investigated as possible sources of raw materials. A wild Mexican yam from the genus Dioscorea provided the plant steroid derivative that served the purpose. With some chemical tinkering, tacking on a molecule here or taking off a molecule elsewhere, scientists succeeded in converting plant steroids into progesterone, and then progesterone into estrogen. Finally, with more chemical magic chemists succeeded in producing derivatives of estrogen and progesterone that were active when taken orally. Most of today’s oral contraceptives are carefully adjusted mixtures of orally active estrogen and progesterone derivatives.

    In the past herbal products were used as emmenagogues or abortifacients to induce menses and control birth. Some of these are still misused and so a short discussion on these is relevant.

    The scriptures of the Zoroastrians, the Avesta, dating back to 600 B.C., warns against feeding moldy grain to pregnant women and animals. Assyrian records from the same time period mention a “noxious pustule in the ear of grain.” These moldy pustules are now referred to as early midwives to induce labor at term or to make women abort have used “ergot.” Ergonovine a useful modern drug derived from ergot is used today in medical practice to induce labor at term and stop postpartum hemorrhage. Such drugs are referred to as oxytocics or substances that cause the uterus to contract.

    There are many oxytocics and emmenagogues found in plants, and pregnant women without proper medical advice must not use them. Broom, pennyroyal, savin and wormwood are other examples of plants with oxytocic properties. Powerful laxatives such as castor oil that are uterine stimulants must also be avoided in pregnancy. The “PDR for Herbal Medicine” published in 2000 by The Medical Economics Company, Inc., gives a comprehensive list of plants to be avoided or used with caution during pregnancy.

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