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    • Thread Starter

    How do exogenous hormones in oral contraceptive pills prevent conception whereas the endogenous ones do not?

    Combined oral pills contain Progesterone and Oestrogen. These two hormones are naturally present in a woman's body. So how come these hormones, when obtained from pills, prevent a woman from becoming pregnant, whereas the same hormones that are naturally present in her body don't do so.
    • TSR Support Team
    • Very Important Poster
    • PS Reviewer

    TSR Support Team
    Very Important Poster
    PS Reviewer
    These hormones are expressed by the body at certain levels which vary over the course of the menstrual cycle so the woman is more susceptible to pregnancy at certain times and less at others. The pill maintains these hormones at a constant high level throughout the cycle ensuring that the woman is protected against pregnancy throughout the cycle.
    • Study Helper

    Study Helper
    Pretty much as the above said, these hormones are regulated and are expressed at different times during the menstrual cycle. The woman may be at a point where she is susceptible to pregnancy and the hormones preventing this are down regulated, giving a pill containing these hormones ensures that pregnancy won't take place during the time period at which the person is susceptible.
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