The Ideal Cycle for Fertility

Women have about 450 menstrual cycles in their lifetime, but many women don’t know much about their cycle. This series will help you understand more about your period, and specifically how your period can give us insight into your fertility.

As with all things fertility, it is never this simple. Some women have the “perfect” cycle and have trouble conceiving, and other women have very erratic cycles and fall pregnant easily. This is just one aspect of fertility that is worth exploring.

..So what is considered the most fertile menstrual cycle?

Length: Between 27-32 days

There have been several studies looking at the ideal cycle length, and not all of them are consistent. This study showed highest rates of pregnancy in women who have a 31-32 day cycle, and this one showed a preference for 30-31 days. This observational study noted that highest pregnancy rates were achieved in women who had a cycle length between 27-29 days. So likely a cycle in the range of 27-32 days is preferred as opposed to the 21-35 day range we often learn about. FYI cycle length is calculated from your first day of full flow, to your next day of full flow.

If your cycle is Shorter:

A shorter menstrual cycle length can be associated with advanced ovarian aging, and in fact on average cycle length decreases by 0.18 days per year of age from age 25-45. Shorter menstrual cycles have been associated with reduced fertility.

If your cycle is Longer:

The most common reason for a longer period (>35 days), is Polycystic Ovarian Syndrome (PCOS). Women with PCOS tend to have higher levels of androgens (testosterone) which can cause acne, facial and body hair growth, and sometimes hair loss in your scalp. Many women with PCOS may also struggle with their weight. All of these hormonal changes can affect ovulation as well, and women with PCOS tend to have longer cycles, or will miss several cycles within a year.

Stress can also cause periods to lengthen, or stop altogether for a period of time. This is called hypothalamic amenorrhea, and is most commonly caused by low body weight or over-exercising, but can also be due to extreme emotional stress. This condition makes ovulation erratic or absent, which can impact fertility.

Other reasons for longer or absent cycles include elevated prolactin levels, thyroid disease, and a condition called non-classical adrenal hyperplasia, which can all impact fertility.

A longer follicular phase is also associated with Vitamin D deficiency, recent use of birth control pills, and marijuana use.

Usually simple blood tests can help determine the cause for your longer periods and then we can pursue treatment options!

Flow: Lasts for 5 days

Cycles with 5 days of bleeding showed the highest rate of pregnancy per cycle, but normal periods generally last from 3-5 days.

A period that is consistently much longer than 7 days, can be due to conditions such as adenomyosis, uterine polyps or fibroids, hormonal changes, or in rare cases, cancer. These conditions can also cause heavy menstrual flow (soaking through a pad or tampon with 1-2 hours). Depending on the size and location of polyps/fibroids these can impact fertility and implantation, and surgical removal might be a good option.

A shorter period, which only lasts 1-2 days can be normal, but can also be a symptom of lower estrogen levels, thyroid imbalance or nutritional deficiencies. 

Colour: Dark Red

Your period blood should be red, slightly darker than blood that you might see if you cut yourself. As the flow slows towards the end of the cycle, brownish blood can be common and is normal. Some spotting before your period is also common, but not ideal as it can indicate lower progesterone levels or structural abnormalities and is associated with decreased fertility.

Small clots (dime-sized) are considered normal, but anything larger than 1-inch in diameter is related to heavy menstrual flow (see a

Pain: Manageable

Ideally, your period comes without much pain at all. However, it’s also common to have some cramping due to uterine contractions and inflammatory messengers (prostaglandins) that are released during your period. These types of cramps tend to get better as you get older, and after having a baby.

If your pain is severe, it can sometimes be caused by another condition, such as endometriosis or fibroids. Endometriosis can have an impact on your fertility – it is estimated that between 25-50% of women with infertility have endometriosis. This type of pain caused by endometriosis may start a few days before your period, and may continue after your period has ended. Sometimes it can even be present all month, and it tends to get worse over time. Many women with endometriosis will also experience pain with intercourse as well.

Cycle Variability: Minimal

Variability between cycles should be minimal – ideally just a few days different from cycle to cycle. Women with high cycle variability had a 50% lower per cycle probability of getting pregnant         when compared with women with low cycle variability.

If you would like to learn more about how Naturopathic Medicine can optimize your fertility, book an appointment with me here.