December 8, 2017

What Is A Normal Menstrual Cycle?

What Is A Normal Menstrual Cycle?

The purpose of the menstrual cycle is to prepare the uterus for pregnancy. Many patients ask what is a normal menstrual cycle? It depends on an orderly progression of hormonal signals and is simplistically divided into the following phases:

1)      Proliferative/ Follicular Phase

2)      Ovulatory Phase

3)      Secretory/Luteal Phase

4)      Menstrual Phase

Cycle Day #1 is defined as the start of vaginal bleeding generally defined as flow not spotting. This is also called by some the Menstrual Phase and usually lasts 2 to 6 days with the median being 4 days of duration.

Cycle length is defined as Cycle Day #1 to Cycle Day #1 of the next cycle and in 90% of women is between 24 and 35 days with15% having an idealized 28 day cycle.

The Proliferative/Follicular Phase of the menstrual cycle is variable in length generally between 7 and 21 days.

Ovulation usually occurs mid-cycle followed by the Secretory/Luteal Phase generally lasting 12 or more days and is more constant than the Proliferative/Follicular Phase.

A Secretory/Luteal Phase less than 12 days called Luteal Phase Insufficiency was historically thought to be associated with infertility. A recent study by Crawford et al published online (FertilSterile Pub 2017Jan 5) found that a short luteal phase was not associated with infertility after 12 months of attempting pregnancy. After adjustment for age, women with a short luteal phase were less likely to become pregnant short-term but not long-term. A short luteal phase (<11 days including day of ovulation) was found in 18% of 1,635 cycles from 284 women aged 30 to 44 years. Significantly more women with a short luteal phase were smokers.

We encourage patients to have a healthy lifestyle to have the best chances of conceiving. If you have any questions, please contact us! We are here for you.

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Joseph A. Hill, III, M.D. Board-Certified in Reproductive Endocrinology and Infertility