Why the Luteal Phase is so Important

Whether you are trying to get pregnant or not, understand your menstrual cycle is vital information about your health. Not only does it allow us to better detect certain hormonal imbalances, even prior to testing, but it allows us as women to become cognitive of how we feel throughout our cycle. Although society sometimes likes to make us feel as though we are “just like men”, we really aren’t and we should use this as our secret superpower rather than seeing it as a weakness. When it comes to your menstrual cycle, there are a few important words or terms we need to understand first as they often get thrown around as meaning the same thing when in fact they don’t. 

So first and foremost, your menstrual cycle isn't your period. Your menstrual cycle is the entire monthly cycle which involves your period (menstruation) as well ovulation, follicular and luteal phase. The menstrual cycle can generally be broken down into two distinct phases, the follicular phase, which starts on the first day of your period (not the last) and end with ovulation.The luteal phase, which we will talk about in more detail today, begins after ovulation, it generally lasts about 12-14 days. The luteal phase will end the day before your period starts. During the luteal phase, we have an elevation in estrogen and progesterone. Estrogen helps stimulate the thickening of the uterine lining, specifically the endometrium, in preparation for pregnancy. 

Even if you aren’t pregnant, this thickening process occurs just in case an egg gets fertilized during ovulation. If an egg was not fertilized, the lining will begin to shed and lead to the start of your period (aka your menses). While estrogen levels rise, another extremely important hormone starts to rise and that hormone is known as progesterone. Each egg is surrounded by what is known as a follicle, this follicle plays an extremely important role to now only surround the egg but once the egg is released, the remainder of the follicle will become what is known as the corpus luteum. The corpus luteum is what releases progesterone (and a small amount of estrogen). Not only does this increase in progesterone help stimulate the thickening of the uterine line, the endometrium, but it also signals to the body to prepare for implantation. 

If implantation occurs, your progesterone and estrogen levels will stay rising as the body prepares for pregnancy. If however, the egg is not fertilized and it does not implant, the corpus luteum will degrade and die and the drop in progesterone and estrogen will trigger your period to start. 

Progesterone is important for implantation but also for supporting the early stages of pregnancy, which means if you are having trouble getting pregnant or staying pregnant, evaluating your progesterone levels and the length of your luteal phase is critical. Too often, if hormone testing is ordered, it is often only ordered during the follicular phase of your cycle. Your doctor will likely tell you to come in for blood work anytime between cycle day 2-5. (Remember, cycle day one is the first day of your period). Although evaluating your hormones during the follicular phase is helpful, it really only gives us one piece of the puzzle. Your doctor may check your progesterone levels in the follicular phase of the cycle and it likely will look normal. This is why at NMD Wellness of Scottsdale, we believe it is important to evaluate your hormones during both the follicular and luteal phase of your cycle. We generally recommend our patients schedule blood work cycle day 2-5 as well as about 5-7 days post-ovulation. If you have irregular cycles, or are having trouble tracking for ovulation, your second blood draw may be adjusted based on your specific needs. 

The goal of testing your progesterone in the luteal phase of your cycle allows us to confirm ovulation and to ideally determine the length of your luteal phase. For some women, they may experience adequate ovulation each month but have a short luteal phase (less than 10 days) which can prevent them from maintaining a healthy pregnancy. In order to confirm adequate ovulation, we generally look for a luteal progesterone serum level of 10ng/mL and above. Again, if your doctor has only tested your progesterone levels in the follicular phase of your cycle, it is normal to see a progesterone level around 0.1-0.3ng/ml. But again, this does not help us confirm ovulation and is why we should really be doing two separate blood draws during the same month for patients with suspected progesterone deficiencies or luteal phase defects. 

Now, even if you aren’t trying to get pregnant, progesterone is extremely critical in promoting a regular cycle and also has a major impact on your mood. This means that if you experience heightened anxiety, weepiness, or major mood swings the week leading up to your period, this may be associated with inadequate progesterone production. Although many women will experience symptoms of PMS the week leading up to their period, if your symptoms are debilitating or significantly impacting your life to the point that you feel like you only have 1-2 weeks out of the month where you feel like yourself, this is NOT normal. I repeat, this is NOT normal. If this sounds like you, it’s time you make an appointment with your doctor.

Causes of Short Luteal Phase 

Although the definitive cause of a short luteal phase is not completely understood, short luteal phases can often be associated with certain medical conditions including endometriosis, PCOS, thyroid disease, obesity and anorexia. The symptoms of a short luteal phase are not always obvious and you might not realize there is a problem until you try to conceive. 

A few symptoms that you may experience include: 

  • Short menstrual cycle - getting your period shortly after ovulation. 

  • Spotting between periods 

  • History of a miscarriage 

  • Less than 3 day periods (when you aren’t on birth control)

Although miscarriages can be associated with a short luteal phase, having a short luteal phase does not mean you can’t have children or that you can’t support a healthy pregnancy. It may, however, mean supplemental progesterone may be prescribed to help support your luteal phase and your progesterone status. Talking to your doctor in a proactive fashion can be an important way to reduce your symptoms and improve your chances of a healthy and happy pregnancy. 

About the Author: Meet Dr. ZenAlissia Zenhausern- Pfeiffer, NMD, FABNE, (commonly known by her patients as Dr. Zen), is a licensed naturopathic doctor board certified in naturopathic endocrinology and the founder of NMD Wellness of Scottsdale, a premier naturopathic medical practice that focuses on helping women to take a proactive approach to their hormone and fertility health. Dr. Zen has been featured as a lead expert in Forbes, Shape Magazine, and Instyle and is deeply passionate about bridging the gap between traditional and natural medicine in the world of fertility. She works with a variety of hormone related issues including PCOS, endometriosis and unexplained infertility. Her goal is to help more women get back into the driver’s seat of their own health to make lasting transformational changes to their health to bring more cute and adorable babies into this world. Read More About Dr. Zen...