Do the Changes in the Menstrual Cycle Due to Age Indicate Changes in Fertility?

It’s no secret that fertility declines with age. The exact age a woman’s fertility declines is unique for each individual. Some women will struggle to conceive in their early 30s due to age-related egg quality and others will find themselves still fertile at 46 years of age (source). Nevertheless, your body may give you some subtle clues that your fertility is changing. Here we examine how a woman’s cycle can change with age and how these changes impact fertility.
 

Have you ever had a stomachache or some other ailment that drove you to look up online to see what may be causing the problem? Then, when you read about the possible causes of the symptoms you are experiencing, what you find convinces you that you may have some terrible disease? The same can be true with fertility. For example, let’s imagine that you’re in your 30s and you travel overseas for vacation. When you return, your cycle of 20 years suddenly comes early and is different than any you’ve experienced in the past. If you are trying to get pregnant you might be concerned and so you look online to see what could possibly be happening. After your research, you are terrified to learn that you might be going into early menopause. However, the less terrifying and more likely explanation might be that the change in your circadian rhythm due to the time zone differences, travel stress and perhaps even the different foods you consumed, affected your menstrual cycle.


Long story short, what is ‘normal’ for an individual woman’s cycle can be hard to define. There are a couple of signs, however, that can give you and your doctor insight about your fertility and whether your cycle is ‘normal’. There are many things that can impact your cycle.  The following events are examples of what can cause a healthy cycle to become irregular (source):
 

  • Age (irregular periods are common during adolescence and when approaching menopause)
  • Stress
  • Extreme emotion (good or bad)
  • Weight Change
  • Excessive physical activity
  • Traveling
  • Breast feeding


Before we launch into what we can expect to experience with our menstrual cycles as we age, let’s review how the length of a menstrual cycle is determined:

 

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To determine your cycle length, you need to know number of days from the first day of your menstrual flow to the start of the next menses. For example, if you start bleeding the morning of November 1st and stop bleeding the night of November 4th and then your next cycle starts on November 29th, your cycle length is 29 days and your period lasts for 4 days.
There are free fertility apps, such as Period Tracker, that can help you keep records of your cycle history if you don’t want to use traditional calendars.

 

If you are on birth control, then your cycle is regulated by the hormones in the pill and you can’t rely on your cycle days to be an indicator of whether or not you are regular. If you are not taking any hormones, the length of your cycle can be an indicator of possible hormonal imbalances and whether or not you are ovulating or ovulating regularly. Regular cycles indicate that ovulation is occurring and that all of the sex hormones are balanced to support natural conception (source).
 

While you may read that the average cycle lasts 28 days, 80% of cycles occur within 21 to 35 days. Typically, menstrual cycles will last two to seven days (source). 
 

The events listed below are not considered ‘normal’. If you do not have  normal monthly cycles, you should talk to your doctor, since there may be health related factors that could make it difficult for you to conceive or maintain a pregnancy (source).

 

  • Bleeding that lasts more than seven days
  • If you suspect that your flow is heavier than it should be
  • Cycles less than 21 days or longer than 38 days
  • Bleeding between cycles or after intercourse  (please note that some women bleed when they ovulate, which can be normal)
  • Missed periods


NOTE: While normal menstruation indicates that you are ovulating, if you are under 35 years of age and have normal cycles, but  still have not gotten pregnant after a year of trying, it is recommended to see a specialist at this time.  If you are 35 or older, the recommendation is to try for 6 months, and if no success, then seek advice from a specialist.


Now to finally address the questions:  how do women’s cycle change as we age and what does that tell us about our fertility?

 

During our 20s-Early 30s:


Ideally your menstrual cycle should occur regularly during your twenties to early thirties. You may have been on birth control for some time. If you are getting off of birth control, the type of birth control you were using and the length of time you were taking it will affect how long it will take to be out of your system. Mini-pills, for example, will be out of your system very quickly and it’s possible to get pregnant as soon as you stop taking them. On the other hand, the shot, such as Depo Provera, may take 3 to 18 months (or longer) after your last shot to get pregnant. 

Please see this blog post to read more about how different types of birth control impact fertility:

 

Menstrual cramps are very common. If they are impeding you from daily activities however, talk to your doctor about your treatment options as well as possible dietary changes. Diet can have an impact on your hormones, which in turn can impact your period (source).

 

During the Mid-to-Late 30s:


Although changes in our regular menstrual cycles can occur at any age, it’s more common for any abnormalities to show up during mid- to late 30s. This might include conditions such as the development of polyps, fibroids, anovulation (lack of ovulation), and endometriosis (growth of endometrial tissue outside the uterus).
 

If you experience bleeding after intercourse or in-between cycles, this can indicate a problem such as endometritis (infection of the inner lining of the uterus) or pelvic inflammatory disease. Remember, not all bleeding irregularities with your cycle mean that you have an abnormal medical condition.  Stress and other issues can also cause changes to your cycle from time to time (source).

 

Fertility, believe it or not, has been shown to start to decline in the late twenties for women and for mid thirties for men. The decline in fertility does not mean that you necessarily won't be able to conceive, but it may mean it will take you longer to conceive (source).


Again, menstrual cramps are very common. If they are impeding you from daily activities however, talk to your doctor about your options as well as examine your diet. Diet can have an impact on your hormones, which in turn can impact your period.

 

During our Late-30s and 40s
 

At this point in our lives, there are normal hormonal changes that can cause our cycles to start becoming irregular. Many women begin to experience changes to their cycles for up to 10 years before entering menopause. When this starts to happen, defining what is ‘normal’ now becomes more confusing, because some women will have longer cycles and others may have shorter cycles. Some will have heavier bleeding and others will have lighter bleeding. This is all considered normal as our bodies transition to the next phase of our lives. Typically, however, women start to have shorter cycles with heavier bleeding. You may also have intermittent menopausal symptoms such as hot flashes and night sweats. 

 

Even if you have irregular cycles, however, you can still get pregnant. If you do not wish to become pregnant during this time, it is recommended to use protection during intercourse until a year has passed with zero menses (source).


If you have started to experience irregular cycles due to natural aging, you may only ovulate 3 times a year instead of 12, but one or more of those eggs may be good.

 

Cycles in the late 40s to early 50s
 

While menopause can occur earlier for some women, the average age of menopause (12 months without menses) is 51 to 52. If you experience menopause before the age of 40, that is considered premature menopause (source).  While perimenopause can begin in the late 30s, it typically begins in your 40s (source). During this time, you can also expect some variation in the number of days of bleeding or the amount of flow. Some cycles may be skipped and then followed by a heavy cycle (source). 


While irregular cycles can be completely normal and healthy at this time, watch for heavy bleeding that is accompanied by dry skin, hair loss and a slow metabolism, as this could signify thyroid issues. Bleeding between cycles or after intercourse can also indicate infection (source).


Whatever your age, if you experience any unusual symptoms, it's a good idea to check in with your doctor. Seeing your provider for an annual physical or a pre-conception check-up is a great opportunity for you to talk about any cycle and fertility questions. While you can’t control for age, you can control for lifestyle factors that can impact your menstrual cycles and therefore your fertility, such as your diet, exercise and weight.

 

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