The menstrual cycle and pregnancy

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  • The mentrual cycle and pregnancy.
    • The menstrual cycle has four stages: 1. bleeding starts (uterus lining breaks down for about four days.)
      • 2.The uterus lining builds up again, from day 4 to 14, into a thick spongy ayer full of blood vessels, ready to recieve fertilised
        • 3. An ovum develops and is released from the ovary at day 14.
          • 4. The wall is then maintained for about 14 days until day 28. If no fertilised ovum has landed on the uterus wall by day 28, the spongy lining starts to break down and the whole cycle starts again.
    • Oestrogen causes the lining of the uterus to thicken and grow. stimulates the release of an ovum at day 14.
      • Progesterone maintains the lining of the uterus. When the level of progesterone falls, the lining breaks down.


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