A woman’s fertile days can be easily determined by conducting the cycle observation card.
The dominant hormones of a fertile period are estrogens which cause the gradual growth of the lining of the uterus (endometrium) and
a particularly strong impact on receptors in the cervix stimulating them to secrete cervical mucus. The nature of this mucus varies with the concentration of estradiol - from a less fertile mucus to a more fertile mucus being optimal for assisting sperm in living. Estradiol also causes opening the cervix, which also helps sperm reach deep into the uterine cavity and fallopian tubes.
In the periovulatory period cervical mucus secretion reaches its peak, gaining the most fertile features: it’s clear, crystal, elastic and gives a sensation of wetness and slipperiness. After a day of its peak the quality of mucus is getting worse and it eventually disappears.
It should be noted that the seminal fluid is alkaline while the vaginal environment is acidic, so without the presence of optimal alkaline cervical mucus the sperm dies within a few hours. The fertile type of cervical mucus creates conditions for the sperm to survive in the reproductive tract up to 5 - 6 days and so intercourse during this period is the most appropriate for couples planning to become parents.
The fertile phase includes:
- about 6 days before ovulation - due to the maximum life span and the ability of sperm to fertilize,
- and 2 days after ovulation - due to the life expectancy of an egg released during ovulation, we consider a period of 24 hours in case of multiple ovulation.
The end of the fertile period is marked by increased basal body temperature to the level of higher temperatures for three consecutive measurements.
For couples planning pregnancy it is important to determine the most fertile days. The appearance of any cervical mucus always means entering a period of fertility, but the day of ovulation is difficult to determine precisely.
Four indicators have been developed helping with the identification of the ovulation moment:
- Appearance of the fertile kind of mucus - elastic, transparent, giving the sensation of being wet and slippery.
- First day of drying which means the presence of less fertile mucus immediately after the peak of mucus symptoms. According to the survey conducted by Billings, Hilgers and Brown that day often turned out to be the day of ovulation.
- The one-day drop in temperature just before the increase to the higher temperatures level, which occurs around the time of ovulation, if it is preceded by several days observation of the more fertile mucus features. Intercourse in the morning of the day with the clear drop in temperature and at the end of the peak of mucus may be very close to the time of ovulation and favours conceiving a child. This temperature drop is probably due to high level of estrogens prior to ovulation.
- First day of temperature rise. The first higher morning temperature may occur few hours after ovulation, so this is a very fertile time. The picture below presents the possible ovulation days depending on the length of the menstrual cycle.
On the diagram below there are presented days of possible ovulation depending on the lenght of your menstrual cycle.
The main issue in the interpretation of the Cycle Card is to determine whether the menstrual cycle may be considered as fertile. If the cycle is biphasic, i.e. the phase of lower temperatures is followed by the phase of higher temperatures lasting at least 10 days, this cycle is correct which means it is fertile. If the phase of higher temperatures lasts less than 10 days it indicates infertility. It sometimes happens that after a certain time cycles can have a suitably long phase of higher temperatures again and there is a chance of becoming pregnant. There is also an effective medical treatment of this luteal phase deficiency.