The Probability Of Getting Pregnant According To The Menstrual Cycle

During the average woman's menstrual cycle there are six days when intercourse can result in pregnancy; this “fertile window” comprises the five days before ovulation and the day of ovulation itself.Just as the day of ovulation varies from cycle to cycle so does the timing of the six fertile days. Reliable methods to predict ovulation are lacking, therefore predicting the fertile window is also unreliable. Clinical guidelines suggest the cycle days during which the fertile window is most likely to occur, but these guidelines are outdated. We provide new estimates based on a prospective study of healthy women.

A study on 221 healthy females published in BMJ discussed the probability of getting pregnant "being in fertile window" according to the menstrual cycle and the image below will summarize the results of this study.

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