This part of the guide is more complicated than my other sections but it will be very useful if you can grasp the basics of what happens during your menstrual cycle. You will then be able to link your fertile signs with your temperature chart and your hormonal changes.
The Menstrual Cycle Phases
The Menstrual cycle can be split into 4 main parts –
- Menses – When you are on your period.
- The follicular phase (time between your period and ovulation). During the follicular phase your ovaries develop several follicles (containing eggs) on their surface which start to mature in the run up to ovulation. As this phase progresses one of these follicles become dominant. The length of this phase varies from woman to woman and from cycle to cycle and the length of this phase will determine the length of a given cycle. The main hormone involved in the follicular phase is estrogen and a woman is most fertile at the end of this phase i.e. the days just preceding ovulation. During this phase, the lining of the uterus thickens in preparation for a fertilised egg. Estrogen levels peak a few days before ovulation causing a change to your cervical mucus to the fertile type.
- Ovulation – This is when the dominant follicle bursts and an egg is released from the ovary. Ovulation is stimulated by a surge in a hormone called luteinizing hormone (LH). This is the hormone which is detected by an ovulation test (LH test) – more on LH tests ‘here’. A woman usually ovulated within 12-24 hours of the LH surge. Estrogen levels plummet following ovulation and you will see your cervical mucus become more creamy and tacky a day or so after ovulation as you are no longer fertile.
- The luteal phase (time between ovulation and your period). The luteal phase generally stays pretty consistent and only varies by a day or so cycle to cycle. The luteal phase usually lasts 12-16 days if you do not conceive. If you discover you have a luteal phase shorter than 12 days then see the section on ‘Luteal Phase Defect’. The hormone Progesterone dominates this phase of your cycle and helps to develop your uterus lining further in preparation for a fertilised egg. Progesterone warms the body and will cause a rise in your basal body temperature. This rise can be detected using a digital ovulation thermometer. If an egg is successfully fertilised by a sperm cell then the fertilised egg will implant into the lining of the uterus approximately 7-10 days into this phase and the development of the uterus lining continues. The pregnancy hormone, hCG is produced when the egg implants and as the pregnancy progresses the levels of this hCG increases and can be detected by a pregnancy test. If the egg is not fertilised then the lining of your uterus will shed (your period) and a new cycle will commence.