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Day 1 is the first day of your period so day 21 is twenty one days after the start of your period. If you are taking Yasmin ovulation is suppressed so we think that your doctor would like you to have a blood test after you have taken Yasmin daily for 21days this means at the end of one packet.
However, it is difficult to know his exact intention.
What is Yasmin?
As we're sure you know Yasmin is a combined oral contraceptive pill so it contains both oestrogen and progesterone. It is normally taken daily for 21days then you stop taking it for 7 days. Then you begin taking Yasmin from the next pill packet so you repeat the cycle.
What happens during a normal menstrual cycle?
The first day of your menstrual cycle is the first day of your period (day 1) when you start to have a bleed. The period usually then lasts anything from 3 to 7 days. During this time the hormones in your body cause your womb to shed the lining (endometrium) that was built up in the previous menstrual cycle.
At the beginning of your cycle follicle-stimulating hormone (FSH) is produced by the pituitary gland in your brain. FSH stimulates the ovaries to produce mature eggs.
Follicles are the fluid-filled cavities in your ovaries. Each follicle contains one undeveloped egg. Normally one follicle becomes the ‘dominant egg’ which matures within the follicle.
The FSH stimulates a number of follicles to develop and start to produce the hormone oestrogen.
Your level of oestrogen is at its lowest on the first day of your period. From then on, it starts to increase as the follicles grow. As the egg matures the level of oestrogen increases which in turn thickens the lining of the womb.
As the level of oestrogen increases it causes a rapid rise in the luteinising hormone (LH).
The rapid rise in the LH causes the dominant follicle to rupture and so the mature egg is released from the ovary and travels down the fallopian tube. This is known as ovulation.
A lot of women think that they ovulate on day 14, but this is an average. Many women will actually ovulate on a different day of the menstrual cycle. Your day of ovulation will vary from cycle to cycle. Some women claim to feel a twinge of pain when they ovulate, but many feel no sensation at all and there’s no other sign that you are ovulating.
How does the combined contraceptive pill work?
The oral combined contraceptive pill works in three basic ways:
1. Oestrogen content of the pill inhibits the secretion of the natural FSH via negative feedback on the pituitary gland and so supresses the follicles developing.
2. The progesterone content of the pill inhibits the secretion of LH and so prevents ovulation. It also makes the cervical mucus less suitable for the passage of sperm.
3. Bothe the oestrogen and the progesterone content of the pill alter the endometrium so discourage egg from embedding.
The Progesterone blood test:
Progesterone levels in the blood provide information and timing of ovulation. Plasma progesterone levels start to rise after ovulation along with the rapid surge in the Luteinising hormone (LH) and they continue to rise for 6-10days. The levels then fall and you have a period.
Blood samples drawn from days 8 and 21 of the cycle will show a large increase at day 21. This will show if ovulation has occurred. During pregnancy the progesterone levels rise as pregnancy proceeds to levels that are higher than those of the regular menstrual cycle.
These blood samples refer to the progesterone levels when you are ovulating. The figure of 3.5 does not make sense because it needs to have the units of measurement for me to make a comment.
Your GP may want to compare the progesterone levels from next blood test at 21days to the previous blood test of 3.5.
We suggest you discuss this matter with your GP who has your full medical history and knows the reason for investigating your progesterone levels.
Answered by the Health at Hand nurses