Recently, a 36-year-old patient came to see me with concerns about her PMS. During the 10 days prior to her period, she’d find herself being mean to her kids, feeling exhausted, bloated, and unable to multitask or accomplish anything the way she used to. She also, tearfully, admitted that her marriage was struggling. “I know I love my husband, but I get so angry at him right before my period, and I never want to have sex anymore,” she told me.
Along with all the symptoms of a luteal phase defect, her cycle day-21 lab test showed low progesterone levels. And she’s not alone: Many women struggle with PMS, and up to 90% of women will experience it during their lifetime—oftentimes, this can be due to a luteal phase defect.
Without knowing what the luteal phase is, however, it can be near impossible to recognize when it’s not functioning at baseline. So, here’s a deep dive into this phase of the menstrual cycle: what it is, how long it lasts, its influence on mood, and more.
What is the luteal phase?
The luteal phase is the time of your menstrual cycle that begins after ovulation and lasts until the moment your period starts.
Let’s take a step back: During the first part of your cycle (the follicular phase), your ovaries produce follicles. This is a predominantly estrogen-dominant time of your cycle. Then, ovulation is triggered by follicle-stimulating hormone (FSH) and luteinizing hormone (LH). This typically occurs between day 12 or 13 of a 28-day cycle—but it really depends on your natural cycle length, which on average is longer than 28 days. In other words, the exact timeline is unique to you.
After ovulation, we step into our luteal phase. This is when the follicle that released the egg closes up and forms this Corpus Luteum. Its primary function is to produce progesterone and to prepare the uterus for pregnancy and implantation of the embryo.
What happens during the luteal phase?
During the luteal phase, your progesterone levels are peaking, and your uterus is preparing for the implantation of an embryo and pregnancy.
I always use the imagery of the first half of the cycle as throwing clean sheets on the bed, and the second half of your cycle is actually making the bed (that’s what progesterone does). During this time you become slightly more insulin resistant, which means there’s a higher level of glucose circulating through your blood, and your body temperature rises. You can find out if you’re in your luteal phase by tracking your basal body temperature, meaning the temperature you are first thing in the morning, before you even get out of bed.
How long is the luteal phase?
Typically the luteal phase lasts between 12 and 16 days.
If pregnancy hasn’t happened, then you will start your period. (The first day you start bleeding is considered day one of your menstrual cycle, and is an indication that the whole process will begin all over again.)
A short luteal phase is shorter than 10 days after ovulation and may be called a luteal phase defect. This can occur if progesterone levels don’t peak, you have anovulatory cycles, or your body is not producing enough progesterone.
In gynecology, we measure peak levels of progesterone somewhere around day 20 to 22 of your menstrual cycle. For example, if you ovulate between days 12 and 14, it’s accurate to measure your peak progesterone levels approximately around seven to nine days after you ovulate. If it’s low [less than 10 ng/ml], we recommend retesting as hormones are pulsatile, and there can be an error.
How to measure your hormone levels.
You can measure your hormones by looking at the levels in your blood, or you can measure hormones during your cycle by checking urinary progesterone levels or salivary progesterone levels. If your progesterone levels are low, it’s worth looking at an ovarian reserve test, this is called AMH (Anti-Mullerian Hormone) test, which gives doctors an idea of your ovarian reserves.
How might you feel during the luteal phase?
With a natural increase in progesterone, your body temperature may feel warmer (remember to track your basal body temperature). You may also feel more energetic since your cells are slightly more insulin resistant during this time, causing an increase in circulating blood sugar.
To keep your blood sugar balanced, you’ll want to be careful taking in any additional glucose or carbohydrates until the last few days of your cycle—i.e. before your period starts. (You can learn more about blood sugar levels and your menstrual cycle here.)
Some women will feel PMS symptoms during the luteal phase, especially if there are lower than optimal progesterone levels. Some may even experience symptoms of premenstrual dysphoric disorder (PMDD), so we’re talking anxiety and depression, bloating, water retention, some brain fog, memory loss, mood swings, sleep disturbance, and a decrease in libido.
You typically get a peak in libido during ovulation and a decrease in libido during the luteal phase. So, I always tell my patients: If you only hate your partner two weeks out of the month, you can likely blame your hormones, not your partner.
Can you get pregnant during the luteal phase?
Fertility peaks at the time of ovulation, and sperm is viable starting 36 hours of the time of intercourse and up to five days in the genital tract. Considering the ovulation cycle, there’s approximately a five-day period within the luteal phase that you can get pregnant.
If you’re on some form of natural family planning and do not want to get pregnant, I’d suggest no sperm in your genital tract for six days before your period starts, and six days after ovulation. This basically puts you in the luteal phase!
Now, it’s almost unfair because when you ovulate, your estrogen and testosterone peak, and that is when your libido is at its highest. Be aware that physiology affects your behavior, and it can work for you or against you!
How can you optimize the luteal phase?
There are several ways to optimize the luteal phase, from food to exercise and more. Here’s what I recommend:
Since your body is preparing for pregnancy during the luteal phase, it naturally has higher glucose levels and more cravings. I recommend eating healthy high-quality, free-range, and organic proteins, when possible. I also recommend healthy fats, like olive oil and avocado, and lots of dark leafy and microgreens to support the gut microbiota and hormone metabolism. Filling up on protein, fats, and fiber will keep you fuller longer and may keep unwanted cravings at bay. (Read more about what to eat during each phase of your menstrual cycle, here.)
That said, you’ll also want to incorporate a stress-relieving activity, like yoga, because cortisol drains progesterone, which can put a strain on this hormonal phase.
During every phase, but in the luteal phase especially, you’ll want to avoid increasing your cortisol levels. I always recommend adding a good meditative practice, continuing to focus on what you’re grateful for, going for a long walk, and scheduling more play and pleasure time.
As mentioned before, you’ll also want to avoid high-carbohydrate foods and simple sugars, since your blood glucose will already be higher.
Other things to keep in mind.
While the menstrual cycle is natural, suffering through it should not be. If you are having challenges with the luteal phase, having difficulty getting pregnant, or have experienced pregnancy loss already, talk to your doctor to get some answers and find healing.
As for my 36-year-old patient, I put her on a healthy fat, protein, and greens diet, as well as other luteal phase optimization plans. Within two months, she reported feeling better, less angry toward her husband, and more confident. The greatest benefit, she said, was having her youngest daughter crawl into her lap and say, “Mommy, you’re smiling again!”
When you get a clear understanding of how your hormones function during each phase of your cycle, the rest of your life will start to feel more balanced, too.
