Summary:
Fertility charting, also known as fertility tracking or natural family planning, is a method used to predict ovulation and increase the chances of conception. It involves tracking changes in a woman’s body such as basal body temperature, cervical mucus, and cervical position to determine her fertile window. This process is based on the science of hormone fluctuations and ovulation. By understanding the science behind fertility charting, couples can use this method to effectively plan for pregnancy or avoid it.
Fertility charting relies on the understanding of the menstrual cycle and the hormones involved in ovulation. The menstrual cycle is divided into two phases: the follicular phase and the luteal phase. The follicular phase starts on the first day of menstruation and ends with ovulation, while the luteal phase begins after ovulation and ends with the start of the next period. The length of these phases can vary from woman to woman, but the average cycle is 28 days.
During the follicular phase, the hormone estrogen is dominant. Estrogen levels rise and stimulate the growth of the follicles in the ovaries, which contain the eggs. As the follicles grow, they produce increasing levels of estrogen, which causes the lining of the uterus to thicken in preparation for a potential pregnancy. At the same time, the hormone FSH (follicle-stimulating hormone) is released from the pituitary gland, which helps to mature the follicles.
As the follicles mature, they produce another hormone called LH (luteinizing hormone). This surge of LH triggers ovulation, which is the release of an egg from the ovary. This surge usually occurs around day 14 of a 28-day cycle, but can vary. After ovulation, the follicle turns into a structure called the corpus luteum, which produces progesterone. Progesterone prepares the uterus for pregnancy by thickening the lining and also helps to maintain a pregnancy if fertilization occurs.

The Science Behind Fertility Charting: How It Predicts Ovulation
The rise in progesterone causes a slight increase in body temperature, which can be detected by tracking basal body temperature (BBT). BBT is the lowest body temperature at rest, and it can be measured with a special thermometer. After ovulation, a woman’s BBT rises by about 0.5-1 degree Fahrenheit and stays elevated until the next period. This temperature shift indicates that ovulation has occurred and that the fertile window has closed.
Another important factor in fertility charting is cervical mucus. Throughout the menstrual cycle, the cervix produces different types of mucus, which can be observed and tracked. In the days leading up to ovulation, the mucus becomes more abundant, watery, and stretchy, resembling egg whites. This fertile cervical mucus helps sperm to survive and swim towards the egg. After ovulation, the mucus becomes thicker and less fertile, creating a natural barrier to prevent sperm from entering the uterus.
Cervical position can also be used as an additional fertility sign. During the fertile window, the cervix is high, soft, and open to allow sperm to enter. After ovulation, the cervix becomes lower, firmer, and closed.
By tracking these changes in the body, a woman can determine her fertile window and increase the chances of conception. Fertility charting can also be used to identify any potential issues with ovulation or hormone imbalances that may affect fertility.
In conclusion, the science behind fertility charting is based on the natural fluctuations of hormones and the menstrual cycle. By tracking changes in basal body temperature, cervical mucus, and cervical position, a woman can accurately predict her fertile window and increase the chances of conception. Understanding this science can help couples effectively plan for pregnancy or avoid it.


