Menstrual cycle know-how: When is Day 1–at the first sign of your period (even if it’s just a few drops) or when it starts to flow?

/Menstrual cycle know-how: When is Day 1–at the first sign of your period (even if it’s just a few drops) or when it starts to flow?

Menstrual cycle know-how: When is Day 1–at the first sign of your period (even if it’s just a few drops) or when it starts to flow?

My Hormonology


The question, “When was the first day of your most recent period?” can crop up quite a few times in a woman’s life: At your gynecologist’s office, if you’re undergoing a medical test or procedure, when you’re family planning or when you’re getting ready to read your daily Hormone Horoscope on this website or in one of my Hormone Horoscope apps.

Pinpointing the first day of your period is key in these instances since it indicates that it’s your Day 1–which is the considered the official start of a new monthly menstrual cycle.

And while you’d think that it’s easy to figure out that day–after all, it’s the first day of your period–sometimes it can get a little tricky. That’s because menstrual bleeding isn’t always as obvious as you’d expect it to be. Sometimes it starts out with a steady flow that continues for several days. Other times, you get slight spotting–which is when you have just a few drops of blood–then nothing for an entire day or more.

When is Day 1 of your menstrual cycle?

So, does Day 1 of your monthly cycle begin–on the day you spot or the day you have a steady flow?

The answer depends on this:

If you have spotting one day, then a steady flow the next, the previous day was your Day 1. That’s because it means that estrogen dropped low enough to trigger the shedding of your uterine lining. It just took awhile for a heavier flow to begin.

However, if you have spotting one day, then nothing else for two or more days, it was likely breakthrough bleeding, which can occur in some women leading up to their period.

By the way, spotting can also happen around ovulation in the middle of your cycle as a result of the egg breaking away from the ovarian follicle, causing slight bleeding.

The takeaway

Once you start seeing red down below toward the end of your cycle, mark it on your calendar. If bleeding continues and gets heavier the next day, then that spotting day was Day 1 of your new menstrual cycle.

If you don’t see anything other bleeding for two or more days after spotting, then continue counting those days as a continuation of your current menstrual cycle.

By | 2017-05-26T07:23:03+00:00 February 9th, 2017|hormonology tip, menstruation, Week 1|9 Comments

About the Author:

Gabrielle Lichterman, founder of Hormonology® and a longtime women’s health journalist, pioneered the growing movement among women to live in sync with their menstrual cycles and know more about all the ways their hormones impact their moods, health and behavior. This movement was launched in 2005 with Gabrielle's groundbreaking book, 28 Days: What Your Cycle Reveals about Your Love Life, Moods and Potential, and her creation of Hormonology®. She offers a variety of tools--including her popular free Hormone Horoscope® app, eBooks, infographics, videos and tips--to share vital information about hormones.


  1. Gabrielle Lichterman December 18, 2017 at 4:43 pm

    Stephanie, if this prolonged spotting prior to menstruation is not typical for you, I’d recommend talking with your doctor about it. That’s a long time to spot before menstruation, so it’s always wise to pass this by your gyn in case it’s a problem that needs to be addressed — especially since you’re trying to conceive.

  2. Stephanie December 16, 2017 at 4:15 am

    I started spotting on the 12th of December brownish color and spotted everyday until the 15th it got heavier and reddish… When does my day 1 start for period as I am trying to conceive and this has thrown me off!! Thanks in advance!!

  3. Pavani September 23, 2017 at 8:05 am

    Thank you for the article, I referred this article to my friends who have similar questions about periods flow. I am still in a dilemma as to when day1 starts. I had red blood spotting (little more than drops) on Sep19th Tuesday night,when I woke up next day Sep20th there is not much on the pad but I saw blood spotting again when I wiped with small clot or tissue like things. After that I just saw only dark brown spotting with very little blood spotting once.On Sep 21st full flow started few hours after I woke up. As I am supposed to start birth control on CD6 I am not sure which day to count as CD1. Is it Sep19th or Sep 21st. Please suggest.

  4. Gabrielle Lichterman September 21, 2017 at 8:16 pm

    If you have a full day of no bleeding after spotting, then you would count the day you start bleeding heavily as your Day 1, Ellinore. So, that would be September 3 in your example.

  5. Ellinore September 21, 2017 at 1:12 am

    Thanks for this article but I am still not sure what it day to start counting if I have spotting lets say on the 1st of Sep then nothing on the 2nd then a lot of blood on the 3rd? do I count the 1st,2nd or 3rd of September as my first day?

  6. Gabrielle Lichterman August 29, 2017 at 4:16 pm

    I’m glad this could clarify things for you, Tamarra!

  7. Gabrielle Lichterman August 29, 2017 at 4:16 pm

    Glad I could help!

  8. Anonymous August 18, 2017 at 4:30 pm

    Great Day 1 demystification, Gabrielle! I really needed this. Thanks for being my go-to gal re: the ever-changing mysteries of my own dang body. Nobody else seems to be talking about this stuff!

  9. Tamarra February 15, 2017 at 2:50 pm

    Ah-hah! Thank you for addressing that because I’ve read conflicting answers to this question in the past. What you are saying makes absolute sense because I tend to have that day of spotting, followed by heavier flow. Now I know for sure to count that first day.

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