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Your Menstrual Cycle: A Fertility Vital Sign


a blog by Eric Levens, M.D., Shady Grove Fertility Center, May 19, 2010

Ready for a fertility fact? Forty percent of women who present with fertility problems aren't regularly producing an egg that can be fertilized (anovulation).

The vast majority of problems with ovulation are accounted for by a condition known as polycystic ovary syndrome (PCOS). Other fertility problems resulting in irregular menstrual cycles include ovarian failure or inadequate signals from the brain that control the menstrual cycle (hypothalamic dysfunction).

To get a better sense of potential underlying fertility problems, at my initial fertility evaluations I often ask “Are your periods regular?” and “How far apart are your cycles?” I want to get a sense of how frequently ovulation is occurring.

The typical menstrual cycle is between 24 and 35 days. When menstrual cycles are irregular in duration or outside this normal range, this frequently indicates a problem regularly producing an egg.

Today, there are many high-tech devices lining pharmacy aisles, all designed to predict ovulation (some even have digital smiley faces). Nevertheless, few tests are as important and as simple as a thorough menstrual history.

In a 2003 study by Malcolm in the journal Obstetrics and Gynecology, the authors reported that a normal menstrual cycle predicted ovulation 99 percent of the time.

While I frequently use high-tech solutions to solve many fertility problems, it's just as important today as ever to remember to listen to a patient's history. It may tell more about the underlying problem than any test.

Once again, I want to thank you for reading my blog and best of luck achieving a Fertile Future.

Comments (17)

I'm feeling tasty and horribly hungry this days And i'm expecting my mestration tomorrow. What might be the cause Of being tasty and hungry?

Aisha, if you are expecting your period you may be confusing PMS for pregnancy symptoms. If you do not get your period you should consult with your OB/Gyn to determine if you are pregnant. Good luck!

Hi Jessie,

Any change in hormones, new medications, or stress can potentially cause changes in your cycle. Also, our cycles change as our ovarian reserve decreases (with age). You should consult a fertility doctor for an evaluation if you are concerned. Give us a call at 1-855-955-BABY (2229) and we will help you find a doctor in your area.


Hi i lost my baby march last year at 21wks due to waters breaking , we decided to start trying again may last year and still nothing , my period was always a 28 day cycle but the last 3 months it has been 32 to 33 day cycle is this normal and why has it changed ?

Hi Natacha,

Any change to our hormones can impact cycle length. Have you tried using ovulation prediction kits or consulted a fertility doctor? We would be happy to recommend a doctor in your area. Give us a call at 1-855-955-BABY (2229).


Hey, I had a mirena IUD for almost 6 years after having my son in 2007. I had it put in 6 weeks after he was born. Before that I had some variances in my cycle but my husband and I were able to conceive naturally but it took us 6 months. Now we have had the Mirena removed 2 months ago. I had my first full cycle last month. It was 33 days long. I used an OPK this month and got a positive yesterday which would put my on course for a 30 day cycle..........what I'm concerned about is by watching BBT I may not be ovulating at this a possibility?? We want to conceive again but I'm thinking that maybe my body hasn't figured out exactly how to get back on track after the horomonal IUD for almost 6 years...................what do you think?

Hello. Since my husband I started trying to conceive two months ago, it seems that my cycles are longer. They used to range from 27-29 days and now (Since March) they seem to be around 33-35 days. March was no good because I was still going by the 27-29 day cycle so we missed our chance to conceive that month. April was the first month that I think I got the timing of sex correct in that we bded on days 14,15,16,18,19,22,24. However, I started my period on May 17. I know we haven't been trying that long, but I can't help but worry that maybe we're doing something wrong.

Hi LP, If you are under the age of 35, it is recommended that you try to conceive for one year before seeking a fertility consultation. If you are over the age of 35, that time is reduced to six months. However, if you are having irregular cycles, it might be a good idea to talk to a fertility doctor right away. Give us a call at 1-855-955-BABY (2229) or email and we can help you connect with a trusted fertility doctor near you. Best, Kim

Hi Kelly, You might benefit from charting your Basal Body Temperature over the course of 3 months or by using an Ovulation Prediction Kit from Day 10 to Day 15 of your cycle. Either method will give you an idea of when you ovulate. Please give us a call at 1-855-955-BABY (2229) if you'd like to connect with a reputable fertility doctor who can help you determine when you are ovulating. Best, Kim

Hello. My periods have always been weird. My cycles range from 29-32 days.. how can I calculate when the right time to try to conceive would be?

What if your period only lasts 2 days...since having my daughter, 2 year ago, my periods have only been 2 days long. Only took 2 months to conceive her, we are now on 20 months ttc #2. Have an appointment scheduled for Shady Grove in January... Thanks!

There are many causes for a change in your menstrual cycles following the birth of your child. At this point you should be seen by an infertility specialist to evaluate the specifics of your condition. It's good that you are coming in.

Dr. Levin,

My cycle has been 28-30 days since I was 15; however I no longer produce the egg white substance I keep reading about that enables sperm to travel where it should go (or I think that's what it does). I haven't seen any of this substance in years. Is there anything I can do about this? Could this be a symptom of anything else?

The fact that you have regular cycles is highly predictive that you are regularly ovulating. Many of the symptoms of ovulation including the increase in cervical mucus can be unpredictable. If you have been attempting to achieve a pregnancy for more than 12 months, you should see an infertility specialist (6 months if you are over 35 years old).

The number of days in your menstrual cycles are within the normal range. However, in certain circumstances, the variability that you mentioned may represent some irregularity in the development of an ovulatory follicle (with a mature egg). Most variability in the menstrual cycle occurs in the first part (the development of the follicle or the follicular phase). The time period following the release of the egg (the luteal phase) is fairly consistent.

The variability that you described may make it difficult in timing the cycle to optimize the chance of conceiving. With that said, it is highly likely that you are producing an egg each month.

Thanks for the comments Dr. Levens. So are you saying that if the menstrual cycle changes from for instance 33 days, to 31 days and then to 28 days in a 4 month span that that may be an irregularity? Thanks again for the important information.

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