My menstrual cycle is 22 days, is it normal?

22 Falling levels of progesterone trigger menstruation and the beginning of the next cycle. From the time of ovulation until progesterone withdrawal has caused menstruation to begin, the process typically takes about two weeks, with 14 days considered normal. For an individual woman, the follicular phase often varies in length from cycle to cycle; by contrast, the length of her luteal phase will be fairly consistent from cycle to cycle.

The loss of the corpus luteum can be prevented by fertilization of the egg; the resulting embryo produces human chorionic gonadotropin (hCG), which is very similar to LH and which can preserve the corpus luteum. Because the hormone is unique to the embryo, most pregnancy tests look for the presence of hCG. In some cases, hormones released during the menstrual cycle can cause behavioral changes in females; mild to severe mood swings can occur.

Although many people believe the average menstrual cycle takes 28 days, a large study of more than 30,000 cycles from more than 2300 women showed that the mean cycle length was 29.1 with a standard deviation of 7.5 days and a 95% prediction interval of between 15 and 45 days. 33 In that study, the subset of data with cycle lengths between 15 and 45 days had an average length of 28.1 days with a standard deviation of 4 days. A smaller study of 140 women performed in 2006 found a mean cycle length of 28.9 days.

The variability of menstrual cycle lengths is highest for women under 25 years of age and is lowest, that is, most regular, for ages 35 to 39. 33 Subsequently, the variability increases slightly for women aged 40 to 44. 33 Usually, length variation between eight and 20 days in a woman is considered as moderately irregular menstrual cycles.

11 Variation of 21 days or more is considered very irregular. A 1979 study of 305 women found that approximately one-third of the subjects had lunar period cycles in length, i.e. , a mean cycle length of 29.5 days plus or minus 1 day.

Almost two-thirds of the subjects started their cycle in the brighter half of the lunar cycle, significantly more than would be expected by random distribution. 35 Another study found a statistically significant number of menstruations occurred around the new moon. The most fertile period (the time with the highest likelihood of pregnancy resulting from sexual intercourse) covers the time from some 5 days before until 1 to 2 days after ovulation.

37 In a 28? Day cycle with a 14? Day luteal phase, this corresponds to the second and the beginning of the third week.

A variety of methods have been developed to help individual women estimate the relatively fertile and the relatively infertile days in the cycle; these systems are called fertility awareness. Fertility awareness methods that rely on cycle length records alone are called calendar-based methods. 38 Methods that require observation of one or more of the three primary fertility signs (basal body temperature, cervical mucus, and cervical position)39 are known as symptoms-based methods.

38 Urine test kits are available that detect the LH surge that occurs 24 to 36 hours before ovulation; these are known as ovulation predictor kits (OPKs).