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Fourteen days before the next period is due, the dominant follicle releases its egg at ovulation. The follicle changes its structure and becomes a corpus luteum (Figure 2.3) in the luteal phase of the menstrual cycle. It continues to function but now it not only releases oestrogens but also progesterone. The progesterone causes a change in the lining of the womb from a proliferative to a secretory pattern. In pregnancy, the lining of the uterus changes its structure to become the decidua which in turn develops into the placenta or afterbirth. Progesterone (pro -in favour and gestation pregnancy) is essential for the development of the decidua. The decidua produces a hormone called HCG (human chorionic gonadotrophin). This HCG is essential to keep the corpus luteum functioning. A cycle is set up with the decidua producing HCG which results in the corpus luteum producing progesterone and this in turn maintains the decidua. From about the twelfth week of pregnancy, the placenta has formed and is self-sufficient in the production of progesterone.
Figure 2.3 The Menstrual Cycle - Hormone Changes In non-conception cycles, there is no HCG to maintain the corpus luteum and it gets smaller and disappears. When the corpus luteum stops releasing oestrogen and progesterone, the endometrium is shed and a period is the result. Progesterone has effects on the endometrium and the breasts but only when they are primed by oestrogen. Progestogens are drugs that have progestogen-like effects. Please click on the required question.
Do you have an unanswered women's health question?Please let us have your general question on our NEW FORUM / MESSAGE BOARDS facility and we will try to answer it for you. I am sure that you will appreciate that we cannot offer advice on the management of an individual's specific problem.
DISCLAIMER The aim of this web site is to provide a general guide and it is not intended as a substitute for a consultation with an appropriate specialist in respect of individual care and treatment. Thank you for your visiting us at 2womenshealth.com. This is the personal website of David A Viniker MD FRCOG, Consultant Obstetrician and Gynaecologist at Whipps Cross University Hospital, London. I do hope that you find the answers to your questions in the patient information and medical advice provided. If you still have unanswered questions, please consider entering them into one of our forums and I will try to assist you.
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