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Looking at Progesterone: Ovulation to Pregnancy
Plus: How Progesterone Drives your BBT Chart...

Progesterone is manufactured by the corpus luteum. The corpus luteum (or "luteal body") is what remains of the collapsed ovarian follicle once ovulation takes place. Once the egg is released by the ovarian follicle into the fallopian tube, the ovarian follicle becomes the corpus luteum and begins to release progesterone into a woman's system.

Following ovulation, this increase in progesterone helps further build the uterine lining during the endometrial "secretory stage". The reproductive function of this process is to prepare the uterus so that a fertilized egg can successfully implant (bind to the mother's womb). In addition to supporting this process of implantation, progesterone may provide additional "pregnancy help" by reducing the chances of contraction in the uterine muscles, as well as by briefly inhibiting female immune response so that a pregnancy is accepted by the body.

During the first half (or preovulatory phase) of a women's cycle, progesterone levels remain relatively low. Following ovulation (the luteal phase), however, the amount of progesterone will increase to help support the implantation of a fertilized egg in the uterus, as well as help maintain a pregnancy by preventing menstruation. Progesterone will also cause a marked warming of the body that is detectable (and measurable) through the technique of basal body temperature charting (read more in the next section on this). Progesterone levels will remain high during your pregnancy.

If you do not become pregnant during a given menstrual cycle, progesterone levels will naturally decrease late in the cycle, leading to the breakdown of the endometrium and culminating in menstruation. If on the other hand a pregnancy is achieved, another hormone will be released by the placenta (hCG), which triggers the corpus luteum to continue the production of progesterone. Thus, the pregnancy will be "maintained" and you will soon experience one of your first exciting pregnancy symptoms - a missed period.

Progesterone and Miscarriage: As progesterone is central to supporting a pregnancy, a deficiency in the production of this hormone may also be a contributing factor in some miscarriages, as well as in "chemical pregnancies" (situations in which a pregnancy is very briefly achieved though ultimately not maintained and menstruation ensues). In the case of a miscarriage, your doctor will be able to provide more information on causes and/or be able test for any kind of deficiency in progesterone. In addition, there are treatments for this issue - from progesterone creams to prescription medications and even natural solutions like acupuncture.

A luteal phase defect may indicate potential issues with progesterone production. A luteal phase defect is typically indicated by a very short (imbalanced) second half of the cycle. By BBT charting, you can determine the length of not just your entire cycle, but also your luteal phase - which should have a duration of ten days or more. To read more about luteal phase defects, click here.

Progesterone and BBT Charting: The easiest way to see how progesterone "drives" your bbt chart is to look at the graph above (which displays changes in hormone levels through a hypothetical 28-day cycle). The two lines of interest for our purposes here are the green line (progesterone) and the gray line (your basal body temperature) - and their relational correspondence. Note how both body temperature and progesterone "lay low" for the first 14 days of this cycle. The reason for this is because the ovarian follicle has not yet released the egg and the cycle is governed thus far by the estrogens.

However, on Cycle Day 14, the egg is released and the ovarian follicle assumes a new and colorful role on the reproductive stage as the corpus luteum. Progesterone production commences and, about a full day after you ovulate, your body temperature rises along with the elevated levels of progesterone (which is the very cause of this "heating up"). Progesterone - and body temperature - remain relatively high through the rest of the cycle, though if you do not become pregnant, both will gradually decrease and ultimately menstruation will take place on Cycle Day 28. If pregnancy is achieved, the corpus luteum receives a hormonal message to keep manufacturing progesterone and temperatures stay high.

BBT charting requires that you start taking your basal temperature on Day 1 of your cycle - which is defined as the first day of menstrual bleeding. Take your temperature every day and record on a graph chart. Your graph should follow a similar (but by no means exact) diagram as the image below. Most educational resources on human reproduction take the twenty-eight day cycle as an example because it represents an average. Your cycle may, of course, be longer or shorter and fall within a normal range.

In order to extract precise fertility information from your chart, you must be exacting in your BBT Charting methodology. There's no room for error - so be rigorous in your charting practices. That is to say, please observe all the guidelines and instructional pointers to ensure you are tracking your body temperature with precision and garnering the facts you need to predict when you ovulate. Easier said than done at, say, 5 AM in the morning... However, a well-kept bbt chart can reward you with a wealth of information and increase your chances of pregnancy.

Basal temperature refers to your resting or base temperature at the minute you wake up in the morning. Take your basal temp immediately upon waking - after at least four to five hours of sleep (do not get up, go to the bathroom, drink water, etc, just roll over, take your thermometer off the nightstand, and place in mouth). Once you get a reading, write it on the chart. To learn more about the details of keeping an ovulation calendar and comprehensive fertility chart, click here. To learn more about special basal thermometers designed especially for fertility purposes, click here.

What Can BBT Charting Can Tell Me?

• The (average) length of your menstrual cycle. Not only will you discover the length of your cycle, you will also find out if your cycle is regular or irregular. These are very important details when it comes to conceiving a baby.
• Phase Info: The length and duration of the phases of your cycle - the preovulatory phase and the luteal phase.
• Fertility issues.... If either cycle phase is out-of-balance (e.g., you chart a shortened luteal phase), you can be alerted to possible issues like hormonal imbalance (often associated with the regulatory relationship between the estrogens and progesterone). Cycle irregularity or the failure to detect bbt thermal shifts (temperature increases) can also indicate hormonal or physiological issues that may require the assistance, council, or treatment of your doctor.
• When you ovulate! By keeping a bbt chart, you know the day you ovulate and you can apply this information to predict fertility for future cycles. A bbt thermal shift takes place about a full day after you ovulate, so it cannot help you predict ovulation for the cycle you are in at the present moment. But by charting patterns, you can pinpoint your fertile window with accuracy for following cycles. If you know when you ovulate, you know when to time lovemaking to increase your conception chances...
• Am I Pregnant? In principle, bbt charting can provide you with an early pregnancy sign if your temperature does not decrease in accordance with previous cycle patterns. This might indicate that you progesterone levels are staying high due to implantation of a fertilized egg.
• To learn about predicting fertility based on related changes in cervical fluids, click here.

Related Articles
Your Ovulation Cycle
More on BBT Charting
Our TTC FAQ

A Week-by-Week Early Pregnancy Adventure

• From Menstruation to Ovulation
• From Ovulation to Conception
• Implantation and the Luteal Phase
• Pregnancy Symptoms
• First Trimester

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