Your Hormones and Your Fertility Signs.
When you begin to observe your fertility signs it is useful to know that these signs correspond to changes in your fertility hormone levels.
Estrogen is the hormone that is dominant during the follicular phase of your cycle (between your period and ovulation). The texture and appearance of your cervical mucus and the position of your cervix are altered by your estrogen levels. An ovulation (saliva) microscopes can also detect an increase in estrogen levels (see my review here).
Progesterone is the hormone that dominates the luteal phase of your cycle (between ovulation and the arrival of your period). Progesterone levels remain high if you conceive and stay high until you give birth. An increase in your Basal Body Temperature (BBT) corresponds with an increase in progesterone levels.
Luteinizing Hormone (LH) is the hormone that surges 12-24 hours before you ovulate and it is this hormone which is responsible for the release of the egg from the ovaries into the fallopian tube. LH tests AKA Ovulation tests/Ovulation Prediction Kits (OPKs) and fertility monitors such as the Clear blue fertility monitor (see review here) are used to pin point this surge and can help to predict impending ovulation.
More about Estrogen:
Estrogen helps to build up the lining of your uterus. This lining is essential as it is what feeds and supports a fertilised egg once it has attached. When talking about fertility, estrogen is often referred to as estradiol and it is produced by the follicles which develop on the ovaries at the start of the menstrual cycle. As a woman gets closer to ovulation the levels of estrogen increase as the dominant follicle takes over production. An increase in estrogen levels can indicate that the follicle is mature and ready for release. This higher level of estrogen also stimulates a rise in LH (Luteinizing Hormone) which should lead to the release of the egg from the ovary. Estrogen also stimulates the cervix to produce more fertile cervical mucus which is watery and preferably stretchy (like egg white). This fertile cervical mucus is vital to ease the passage of the sperm to the fallopian tubes from the vagina. Higher levels of estrogen also results in the cervix becoming soft and more open to allow sperm to enter.
More about Luteinizing Hormone (LH):
Luteinizing Hormone (LH) peaks just before the egg is releases from the ovary. It is the hormone that stimulates the egg to rupture out of the ovarian sac. The surge in LH may be detected in your urine by using LH tests AKA ovulation tests or Ovulation Prediction Kits (OPKs). A positive LH test may indicate that a woman will ovulate within 12-24 hrs. LH levels rise and fall over a 24-48 hr period and may remain high the day of ovulation. A rise in LH occurs in the morning but cannot be detected for 4-6 hrs so doing an LH test in the morning is not ideal . It is recommended to test later on in the afternoon/early evening for this reason. If you are using a test strip then the test line needs to be as dark or darker than the control line. Below is an example of a positive test.
As a woman always has LH in her system in small amounts there will always be a test line on the test. It is how dark the line is that is important to detect a surge. LH tests are very useful in warning a woman of impending ovulation. You should never totally rely on LH tests to predict ovulation however. You need to correlate test results with your fertile signs e.g. the appearance and texture of your cervical mucus. They may be particularly helpful if your temperature chart is confusing. If a woman has long and irregular cycles then the most well-known high street brands (e.g. clear blue) can prove very expensive. The cheaper ovulation test strips are just as effective and you may purchase as many as 50 here for around £7 – See product page here.
More about Progesterone:
Progesterone levels increase following the release of the egg from the ovary i.e. the luteal phase of the menstrual cycle. Before a woman ovulates, she will have progesterone in her system but levels are low. Following ovulation, Progesterone is produced by the empty sac left behind on the ovary by the released egg (the corpus luteum). Progesterone levels increase quite dramatically and these higher levels are vital in maintaining and building the uterus lining in preparation for a fertilised egg. If a woman falls pregnant then progesterone levels remain high until she gives birth. Progesterone is a warming hormone and an increase in levels may be detected by recording your Basal Body Temperature (BBT) using a BBT ovulation thermometer (a digital thermometer). Progesterone levels cause a woman’s BBT to remain high throughout her pregnancy.