Generally, a woman’s most fertile time happens between days ten and seventeen of the menstrual cycle. However, that window of fertility takes place in just 30% of women. Even with regular as clockwork cycles, nearly all women are fertile outside of this narrow window of their monthly cycle. Deciding when to have sexual relations to avoid pregnancy or to improve the chance of pregnancy, requires more information than simple timing.
Predicting Ovulation with the Rhythm Method.
The rhythm method requires accurate record keeping. You will need to record the history of a minimun of six menstrual cycles by recording the first day of each period and the period length. Determine the length of your shortest and your longest cycle. Subtract eighteen from the number of days of your shortest cycle. This will be the first day of your fertile period. Subtract eleven from the number of days of your longest cycle. This will be the last day of your fertile period.
Which Factors Affect the Length of the Menstrual Cycle and Periods of Fertility?
Menstrual cycles do vary. The length of time between cycles is affected by circumstances such as stress, sickness, and nutrition. Once ovulation has occurred, the optimal period for fertilization is twelve to twenty four hours. In addition, sperm cells are viable within the female’s body for three to five days. All of these factors combine to make forecasts of fertility and ovulation problematical.
What are Some Signs that Ovulation has Occurred?
Women may feel a range of signs when ovulation occurs. These symptoms may include changes in the consistency of cervical fluid, a twinge on one side of the abdomen, an increased desire for sexual activity, light spotting, a change in position of the cervix, increased firmness of the cervix, raised temperature on a body temperature chart, higher levels of luteinizing hormone, tenderness in the breasts, sharpened sensory perceptions, or abdominal bloating.
Can Ovulation Happen Right After Your Period?
Women with short or irregular periods can ovulate right after the period ends, although this is quite rare. Suppose that a woman has a cycle that is 21 days in length and she bleeds for seven days. Ovulation is predicted twelve to sixteen days before the next period. A woman may ovulate shortly after her period. There is also a chance that she may also ovulate during her period. The majority of women will not ovulate during these times, but keeping accurate records of period length and intervals between periods can provide a good estimate of when ovulation is most likely to occur.
British Medical Journal; Wilcox, Allen J
The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study
2000; volume: 18; no:231; pages: 1259-1262
American Pregnancy Association
Ovulation Frequently Asked Questions
Rhythm Method for Natural Family Planning