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What is a Luteal Phase and why is it important?

In an earlier post I talked about 4 things you need to know before trying to get pregnant. One thing you need to know is the length of your luteal phase Here I’ll define luteal phase, tell you what it is, what you can learn from it, and why that is important.

The luteal phase is the the post-ovulatory portion of a woman’s cycle (or, the time between when you ovulate, and when you get your period).  The luteal phase is named for the corpus luteum, which is what’s left of the follicle that was housing the egg that got released at ovulation. The corpus luteum produces progesterone, which your body needs to ripen the endometrium (uterine lining).  Progesterone turns the endometrium into a nice soft bed in which a fertilized egg can implant, and a baby can grow. The ripening of the uterine lining happens every cycle after an egg is released, whether or not the egg is fertilized.  If the egg is not fertilized, the corpus luteum stops producing progesterone after about 12 to 16 days.


Women’s luteal phases generally don’t vary by more than a day or two, per the particular woman.  That means that if your luteal phase is usually 12 days long, occasionally it might be 11 or 13, but it probably won’t ever be 15 or 16.  Your friend Liz might have a luteal phase that is usually 15 days.  Hers might sometimes be 14 or 16, but it will probably never be 12.

The luteal phase lasts from ovulation until menstruation.  Menstruation happens when the corpus luteum stops producing progesterone. Think of progesterone like the music at a party.  Think of the endometrium as the guests at that party.  When the music shuts off, the guests leave.  That’s how it is with progesterone, when the corpus luteum stops producing progesterone, the endometrial lining is shed through the vagina, and you have your period.  So very simply put, the luteal phase is the post-ovulatory phase of your fertility cycle. It starts at ovulation and ends at menstruation.

So What?

The length and quality of your luteal phase can tell you a lot about your fertility. If your luteal phase is less than 10 days, you might have a hard time staying pregnant.  This is because if the corpus luteum craps out after 9 days, and stops producing progesterone, that lovely soft bed it made for the fertilized egg will break loose from the uterine wall and your period will commence before the fertilized egg ever gets a chance to make it from the fallopian tube, where fertilization occurs, to the uterus, where gestation happens.  And with no place for a fertilized egg to implant and grow, pregnancy can not occur. The difference between fertilization and implantation is this: Fertilization is when the sperm and egg meet and become a zygote.  This fertilized egg will not become a baby unless it attaches to the endometrium and grows there.  Pregnancy begins at Implantation, when the zygote sets up shop in the endometrium.  Similarly, if you have a luteal phase that suggests low progesterone levels, (if your temperature consistently falls below your coverline, for instance) you may have a hard time sustaining a pregnancy.  Even though your luteal phase may be a healthy length, if there is not an adequate amount of progesterone to properly ripen the endometrium, a fertilized egg will not have the foundation it needs to grow.

It’s important to know these things because if you’re trying to have a baby you want to have the best possible chance at carrying the pregnancy to term. And if your luteal phase is sub-optimal that’s information you want to have, so you can do something about it. The best way to know the length and quality of your luteal phase is to start charting your fertility.

What fertility charting enables you to do is gather the relevant information about your body and its ability to create and sustain life, so you know if you’ve got a good chance at a healthy pregnancy.  If there are some issues that would make the path to motherhood difficult, you’ll have a record of them, and can share that information with your healthcare provider, in order to find the best way to remedy the situation. You can hit the ground running, instead of having to do months of invasive testing procedures to find out what’s going on.

In conclusion, luteal phase is the post-ovulatory phase of your menstrual cycle, dominated by progesterone.  Charting your cycle can tell a lot about your luteal phase, like if it’s too short, or if your progesterone level might be low. Both of those can impact your ability to have a baby.  Armed with the right information, you’ll have the best possible shot at a healthy pregnancy.

Have questions about luteal phase?  Ask in the comments… I’ll answer them. :)

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  • doreen obeng amponsah

    7:34 amSeptember 18, 2012

    I can’t get the days I ovulate
    due to cycles 29,30,31
    have 2 kids but now my progesterone level is lowered and can’t conceive what do I do

    • Kati Bicknell

      8:08 amSeptember 19, 2012

      Hi Doreen,

      I’m not quite clear on the first part of your question. Could you explain further?

      How do you know you have low progesterone? Have you been charting? If you give me more information I will do my best to help you.

  • Di421

    8:00 amOctober 1, 2012

    Thanks for the information! I am currently charting and am starting my third month off birth control pills. My first month off seemed to go fine (no pregnancy though). My second month showed a short luteal phase of only 8 days. I have started 50 mg of Vit. B6 with this new month as I have read that this can help length the luteal phase. We’ll see how it goes!

    • Kati Bicknell

      6:25 amOctober 18, 2012

      You’re welcome! I hope the post was helpful. If you have any questions please ask. We are here to help. :)

  • Beth

    8:47 amDecember 13, 2012

    Thanks for writing this up. I’ve been wondering about whether a too short luteal phase could flush out a fertilized egg. Would you please list your references used for this article? I enjoy research, and I’d love to read them. Thank you.

    • Kati Bicknell

      8:52 amDecember 14, 2012

      Hi Beth,

      I’m glad this helped you! The book, Taking Charge of Your Fertility by Toni Weschler is a great place to start if you’re interested in learning more about fertility charting. Have fun! :)

  • Michelle

    12:36 pmDecember 23, 2012

    It’s my 4th cycle since I started charting my BBT. Now I also use OPK to track when I ovulate. I wonder when the temperature shift begins. Is it when I get positive (2 lines) result, I can tap on the “temperature shift” box? Thanks a lot!

    • Kati Bicknell

      7:25 amJanuary 1, 2013

      Hi Michelle,

      Your temperature shift begins on the first day that your temperatures are above your coverline. Though you can not correctly mark this until you’ve seen 3 days of high temps, just so you know it’s an actual temperature shift, and not a fluke high temperature.

      If you have more questions just let me know. :)

  • Elizabeth

    1:24 amJanuary 4, 2013

    Is it possible that the luteal phase changes as we age. I had baby #1 at 21 years. Second was at 26. Now i am 35 and i had a miscarriage 2 months ago. Would like to conceive before i turn 36. I think my luteal phase is very short. I get this conclusion from the follwing. Nov. 14, 2012 i had a miscarriage. Next dr. visit was Dec. 3rd and she said according to the ultrasound that i should ovulate the 4th or 5th of Dec.. Then i got my next period Dec. 12th. That is only about 7 days. Could i be wrong or misunderstanding?

    • Kati Bicknell

      8:22 amJanuary 4, 2013

      Hi Elizabeth,

      Yes, it’s common for luteal phases to change length as women get older.

      As for your specific questions, due to the overwhelming number of questions we are receiving on the blog, please ask us any specific personal questions through the Ask an Expert feature of our Kindara for iPhone app. Myself and other fertility counselors will be happy to help you out there. :)

  • Bravehart

    4:25 amJanuary 7, 2013

    Hello. This is my first time of logging to your blog and I loved every bit of it! I have lots of questions! I had my last period on the 18th of December and it ended on 21st(its quite consant). I want to know when am likely to ovulate and also my luteal phase. Moreover, can I get pregnant during my luteal phase? Thanks!

    • Kati Bicknell

      6:37 amJanuary 8, 2013

      Hi Bravehart,

      I’m glad you found us! If you’re new to fertility charting, check out this post.

      Due to the overwhelming number of questions we are receiving on the blog, if you have specific questions about your cycle, please ask them through the Ask an Expert feature of our Kindara for iPhone app. Myself and other fertility counselors will be happy to help you out there. :)

      And in general, a woman can not get pregnant during her luteal phase. (That is assuming you are trying to get pregnant, there is a rule for the Fertility Awareness Method if you are avoiding pregnancy that has the fertile period ending 3 days after the postovulatory temperature shift.)

  • Elaina

    9:32 amJanuary 8, 2013

    Hi…My husband and I have been trying to get pregnant with baby number 2 for a year now. I have been charting for 4 months and taking a prenatal vitamin. I generally have a 28/29 day cycle with ovulation on days 18/19 leaving me with only a 10 day luteal phase (OPK’s and temperature shifts are both in line with this). My question is if a 10 day luteal phase is long enough to support a pregnancy or if I should consult with my OB/GYN?

    • Kati Bicknell

      4:39 amJanuary 10, 2013

      Hi Elaina,

      Due to the overwhelming number of questions we are receiving on the blog, if you have specific questions about your cycle, please ask them through the Ask an Expert feature of our Kindara for iPhone app. Myself and other fertility counselors will be happy to help you out there. :)

  • SummerSmith

    10:45 amJanuary 25, 2013

    I have a question if my ovulation day is on the 12th and my menstrual doesn’t start till the 26th and I had unprotected sex where my man ejaculated within that time between, and is I guess I’m asking being my ovulation day was the 12 and my menstrual doesn’t start till the 26th I have 14days of Luteal Phase and I was wondering during that time is it possible to get pregnant???

    • Kati Bicknell

      8:09 amJanuary 26, 2013

      Hi Summer,

      Thanks for your question! We have been getting so many questions on the blog that we’ve chosen to now only answer general fertility charting questions here. For specific questions related to your situation it’s best to use the Ask an Expert feature in the Kindara iPhone app. Our fertility counselors will help you get this all sorted out. :)

      Best of luck to you!

    • Beth

      11:35 amJanuary 26, 2013

      It is not possible to get pregnant from having sex during the luteal phase. The days from the second day after ovulation until the start of the period are considered “safe” days for people who are looking to avoid pregnancy.

      • Kati Bicknell

        8:34 amJanuary 29, 2013

        Hi Beth,

        Just to clarify, going by the rules of the Fertility Awareness Method the days that are considered infertile are from the evening of the 3rd consecutive day after the temperature shift, AND the evening of the 4th day after the cervical fluid Peak Day, both conditions must be met at the same time. Two days after ovulation is not considered infertile by the rules of the Fertility Awareness Method. Out of curiosity, where did you learn that it was? There is a lot of misinformation about fertility charting out there.

        • Beth

          10:29 amJanuary 29, 2013

          Those rules exist because even when you have a pretty good idea of when you ovulated, and you have very regular cycles, there are always outliers, so you can’t be absolutely certain that you ovulated until those conditions have been met. So, you’re not still fertile two days after ovulation (because the egg has degraded by then), but you shouldn’t have intercourse that day because you can’t be sure that you have ovulated at that point. Looking back at it, you have a better idea of what happened when. Since Summer already knew her ovulation date and was looking back on her cycle, I thought it would be more helpful if stated that way. I tend to think in the moment, so I didn’t think that she might need more info for future cycles.

  • Tonia

    5:11 pmFebruary 1, 2013

    Hi there,

    I’m in my luteal phase… 9 dpo. I am having
    What feels like ovulation pains, only constant
    On the left side.
    Does the corpus luteum over act if one
    Is pregnant? Or is this normal to feel this
    Pain if one is not pregnant?

    • Kati Bicknell

      2:18 amFebruary 2, 2013

      Hi Tonia,

      I can’t say for sure what that pain might be. If it continues and gets worse you may want to speak with your doctor about it.

    • Elizabeth

      6:00 pmFebruary 7, 2013

      What i learned is that even while pregnant you can get the sharp pains like when ovulating. I am currently 8 weeks and still have the pains. Dr says it is perfectly normal.

      • Kati Bicknell

        6:03 pmFebruary 8, 2013

        Hi Elizabeth,

        I’m glad you got that sorted out, and that it’s normal. Thanks for updating us. :) Have a great pregnancy!

  • Mary

    12:57 pmMarch 15, 2013

    Hi, there:

    I’m 37 and my husband and I have decided (albeit a little later in life than most) to TTC. I just began charting a few days ago (so no expert yet) but I’ve always been in tune with my body and cervical fluid (i.e., aware there was a change, not necessarily what that change meant – until now). Nevertheless, I think my most recent ovulation happened seven days ago; however, my BBT readings since that time have ranged only from 97.3 to 97.6, which according to your literature, seem a bit low. (As an aside, I took them upon getting out of bed when I just read I should instead take them upon waking, *before* rising, so maybe this has influenced my readings?) My bigger worry is that these relatively low luteal-phase temperatures mean my body isn’t producing enough progesterone, which concerns me with respect to maintaining the viability of a pregnancy. Too soon to panic? Any feedback you can provide would be most appreciated. (And thanks for creating a wonderful app, then tying it to such useful information! I’ve learned more about my reproductive health in the last week than in the 37 years before!)


    • Kati Bicknell

      1:28 pmMarch 15, 2013

      Hi Mary,

      Too soon to panic! How about, no panicking until at least 6 months into charting… and even then, panic never does anyone much good. :)

      It’s a wonderful idea to chart your fertility! and GREAT that you were already in tune with your cervical fluid.

      When using the Fertility Awareness Method, the way to confirm that ovulation happened is to look for at least three days of temperatures that are at least 0.1 degree higher than the highest of the previous 6 temperatures. If you don’t have at least 9 days of GOOD data, (meaning that you took your temperature correctly, read more about that here. then you can’t really confirm that ovulation happened. Does that make you feel better?

      In this beginning learning period go easy on yourself, gather good data, and ask lots of questions from good resources. No need to panic. :) Any general fertility charting questions I’m happy to answer here, and if you have more specific questions you might want to make use of our Ask an Expert feature in the Kindara app.

      Best of luck to you. :)

      • Mary

        1:48 pmMarch 15, 2013

        Thanks, Kati. That’s reassuring (the over-achiever in me tends me toward getting ahead of myself). Will relax and just enjoy the trying (charting along the way). I’ll be sure to follow up in time if need be. Thanks again!


  • Mary

    1:12 pmMarch 15, 2013

    Correction to last post/question: I think I’m five (not seven) DPO (not that two days will make much difference in your reply). Thanks!

  • Babss

    4:35 pmMarch 15, 2013

    This is my second month of charting and I have found that the time that my BBT dips is quite long. This one is working on a week. Is that normal?
    Great article BTW.

    • Kati Bicknell

      1:23 pmMarch 18, 2013

      Hi Babss,

      Congrats on starting to chart! I hope you find it useful. :)

      I think you’re probably talking about “ovulation dip” right? Most women do not get an ovulation dip. If you’re finding that your temperature is lower than “normal” for about a week, there could be many reasons for that. We’d need to see your chart and ask you some more questions to get to the bottom of this. You can use the Ask an Expert feature in the Kindara app, and we’ll help you get this all sorted out.

  • Tara Singh

    7:19 amMarch 17, 2013

    I have been charting my BBT
    and using OPK for 6 months.
    I ovulate on cycle day 17, but
    my cycles are very short (25-26)
    days. Does this mean I can’t get
    pregnant? Is there anything I can
    do to lengthen my luteal phase?

    • Kati Bicknell

      1:27 pmMarch 18, 2013

      Hi Tara,

      Yes, there are lots of things one can do to lengthen a short luteal phase. One thing is to make sure you’re getting enough healthy fats in your diet, (organic butter, avocado oil, fish oil, etc)

      Working with a herbalist can also be effective, as can acupuncture. Even a western doctor can help, often prescribing progesterone cream, or other things. If you do anything over an above changing your diet, it’s certainly best to work with a professional.

      Best of luck!

  • Danielle

    4:19 pmApril 2, 2013

    My luteal faze is long, and not short, I ovulate on about cd 12-14 and have a 31-33 day cycle… Do you have any clue what could cause this, or if it’s affecting me?

    • Kati Bicknell

      12:31 pmApril 3, 2013

      Hi Danielle,

      To answer your question I’d need more information. The Ask an Expert feature of the Kindara app is great for this. Our fertility counselors will help you get this figured out.

      Best of luck!

  • Amy Ang

    12:33 amApril 3, 2013

    Thanks for the information.
    I really enjoy reading and received much knowledged from your articles.

    Been trying to get pregnant for the past 3 yrs..
    Still no news.
    I have a 31 days cycle, 5 days menstrual.
    My next estimated mensus will be on 12th April.

    I really want to know at which stage i need to do or intake what kind of nutrition to boost conception.

    can you help me?


    Best regards, Amy

    • Kati Bicknell

      12:32 pmApril 3, 2013

      Hi Amy,

      Thanks so much for getting in touch with us. I hope we can help you. :)

      Charting your fertility is a great way to learn about your body, and to see when you are fertile, so you will have the best chance of conceiving. Have you started charting yet?

      If you are new to fertility charting I suggest reading this article on our site:

      That’s a good place to start! :)

  • Chels

    8:45 amApril 14, 2013

    Hello I’m just wondering if you could give me some information. I has a mmc 3 months ago, my lp is 10 days long I’m worried I won’t get pregnant again and it’s short, do I need to see a doctor to get my lp lengthened thanks x

    • Kati Bicknell

      10:27 pmApril 25, 2013

      Hi Chels,

      There are lots of natural ways to lengthen your luteal phase. Start by eating a healthy diet rich in good fats like avocado and hemp seed oils, fish oil, and organic butter. :)

      Acupuncture has also been shown to help with fertility issues. And yes, you could absolutely talk with your doctor about this.

      Best of luck to you.

  • Emily

    11:42 pmApril 22, 2013

    Hi, thanks for this information!
    I had a very short LP (3 days) due to breastfeeding. I used 100mg vit b6 and bioidentical progesterone cream. In one month it increased my lp to 10 days! Anyway, a few months later I am pregnant – now 4+2. Hooray! :) I’m just wondering…is it still necessary to take the b6 and prg cream?


    • Kati Bicknell

      10:09 pmApril 25, 2013

      Hi Emily,

      That would be a question to ask your health care provider. Progesterone cream can be tricky, and it’s best to work closely with your doctor or other health care provider who knows your complete health history, in order to help you get the best results.

      Best of luck!

  • jenny

    9:23 pmApril 24, 2013

    So someone can’t get pregnant during her luteal phrase

    • Kati Bicknell

      10:03 pmApril 25, 2013

      Hi Jenny,

      The luteal phase technically starts on the first day of the temperature shift, and if trying to avoid pregnancy you must wait for the evening of the 3rd high temperature (as well as observe the cervical fluid Peak Day +4 rule) to consider yourself infertile. So yes, for MOST of the luteal phase a woman can’t get pregnant, but for the first 3 or 4 days it’s still possible.

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