Along with all the symptoms of a luteal phase defect1, 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. 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. 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. 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 cycles2, 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. 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. 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! 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. As mentioned before, you’ll also want to avoid high-carbohydrate foods and simple sugars, since your blood glucose will already be higher. 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.
