What is a luteal phase defect?

Written by: Dr. Amy Beckley, PhD, Founder and Inventor of the Proov test the first and only FDA-cleared test to confirm successful ovulation at home.

Written on 6/4/21

 what is a luteal phase defect?

A luteal phase defect (or short luteal phase) can make it more difficult to get pregnant.

If you’re in tune with your cycle, you’ve probably heard of the luteal phase. This phase makes up the second half of your cycle, between ovulation and your period.

What many women may not know, however, is that a luteal phase defect (or short luteal phase) can make it more difficult to get pregnant. Keep reading to learn more about luteal phase defect!

What happens during the luteal phase?

The average menstrual cycle lasts 28 days (although note that a normal cycle length can range from 21 to 35 days!) and ovulation splits our cycle into two main phases: follicular and luteal. The follicular phase is dominated by estrogen production, as the follicles grow, mature, and prepare to release an egg.

Once ovulation occurs — meaning an egg was released — the luteal phase begins. This phase lasts until the first day of your next period. Formed in the place of the empty  follicle from which the egg was released, the corpus luteum starts producing progesterone, making the uterine lining “sticky” enough for implantation, in the case that fertilization occurs.

Just as there are only a few days each cycle when conception is possible, there are also only a few, specific days each cycle when implantation of an embryo is possible. This is known as the implantation window.

The implantation window is a period of time during the luteal phase that lasts about 4 days. This is when it’s important for your uterus to be most receptive to the embryo.

In order for implantation to be successful, the uterine lining must be able to receive an embryo which, is where progesterone comes in. Without enough progesterone, it can be more difficult — but not impossible — for an embryo to implant.

Generally speaking, implantation may occur anytime between 6 and 12 days post ovulation, but studies show implantation is most likely to occur on days 8, 9, and 10 post ovulation.

 what is a luteal phase defect?

Implantation may occur anytime between 6 and 12 days post ovulation, but studies show implantation is most likely to occur on days 8, 9, and 10 post ovulation.

What is a luteal phase defect?

A luteal phase defect occurs when the uterine lining doesn’t develop as it should each cycle. This causes it to shed too soon, meaning your period begins too soon and the luteal phase is shorter than it should be.

A healthy luteal phase is typically 11-12 days long, giving the fertilized embryo plenty of time to implant. Any length shorter than 11 days can be considered a luteal phase defect and could make it harder for implantation to occur and be successful. Luteal phase defects can also be characterized by low progesterone levels during the luteal phase, even if the length is healthy.

What causes a luteal phase defect?

As we mentioned, progesterone is responsible for creating a healthy and receptive uterine lining. Progesterone must rise and remain elevated for several days during the luteal phase to ensure a healthy length. Without enough progesterone, the uterine lining may not be prepared to receive an embryo, causing it to shed too early and end the luteal phase.

Low progesterone or a luteal phase defect can be caused by many different factors, including:

  • Polycystic Ovarian Syndrome (PCOS): PCOS is by far one of the most common causes of anovulatory infertility. Without ovulation, there is no empty follicle to produce progesterone. Even when they do ovulate, PCOS patients are at higher risk for having suboptimal progesterone levels. 
  • Endometriosis: Endometriosis might cause increased estrogen levels in comparison to progesterone and therefore, low serum levels during the mid-luteal phase. 
  • Hypothyroidism: T3 and T4 hormones regulate the entire endocrine system. Hypothyroidism means the thyroid gland isn’t producing enough of these two important hormones. Without enough T3 and T4 your body may struggle to produce enough progesterone.
  • Unhealthy body weight: In order for ovulation to happen, women need to have a certain percentage of fat. When this percentage is either too low or too high, ovulation may not happen or ovulatory function may be poor.
  • Stress: Stress may cause your cortisol (the stress hormone) levels to spike. When your body recognizes that it needs more cortisol, it will “steal” resources from other, less important hormones — like progesterone — to make more cortisol.
  • Excess exercise: Too much exercise, like Crossfit or marathon training, can cause physical stress. Our bodies do not distinguish between psychological and physical stress, therefore both can increase cortisol levels.

How do I know if I have a luteal phase defect?

Usually women who track their cycles may notice something’s off with their luteal phase when the period of time between ovulation and their next period is shorter than 11 days. You may also notice low progesterone levels via a blood or urine-based test. Even if you’re not tracking, a luteal phase defect can cause light, brown spotting that may start as early as one week after ovulation.

Sometimes there may not be any spotting and you just notice your period is a few days early. Low progesterone may sometimes be accompanied by premenstrual symptoms such as:

  • Sore breasts
  • Mood swings
  • Anxiety
  • Sleeping disorders
  • Bloating
  • Fatigue

Because there are several causes for spotting during the luteal phase, you should definitely consult your doctor if you suspect you have a luteal phase defect. If you’re experiencing some of the symptoms or still just aren’t totally sure, it may be worthwhile to confirm successful ovulation.

Successful ovulation refers to an ovulatory event in which an egg was released and progesterone levels rise and remain elevated for long enough during the luteal phase. If there is not enough progesterone produced after ovulation, this is considered “weak” ovulation which can make it more difficult to successfully conceive.

Proov PdG tests are the first and only FDA cleared PdG tests to confirm successful ovulation at home. PdG is a urine metabolite of progesterone. After progesterone circulates through the bloodstream, it is metabolized by the liver and excreted from the body in urine as PdG.

Proov testing protocol recommends testing PdG levels daily on days 7, 8, 9, and 10 past peak fertility (i.e. a positive LH test) to confirm successful ovulation. We like to see 3-4 positive PdG tests (with a positive on day 10 past peak) to confirm that ovulation was in fact successful and enough PdG was produced during the luteal phase.

If you get anything less than 3 positive PdG tests or do not get a positive result on day 10 past peak, this could be a sign of “weak” ovulation and low PdG production, which could make it more difficult - although not impossible - to successfully conceive.

In fact, a recent study showed that successful pregnancy rates went from 19% to 91% when PdG levels were elevated during the 7-10 days past peak window. So while it’s possible to conceive and go on to have a healthy pregnancy with low PdG, your chances are much better when PdG is elevated during that key 7-10 day window!

 what is a luteal phase defect?

Proov testing protocol recommends testing PdG levels daily on days 7, 8, 9, and 10 past peak fertility (i.e. a positive LH test) to confirm successful ovulation.

How are luteal phase defects treated?

There are several ways to increase progesterone to support the luteal phase. We always recommend consulting your doctor to choose the best treatment path for you and your goals!

Sometimes, natural remedies can help increase progesterone and the length of your luteal phase. Things like diet changes and seed cycling have proven to be effective.

You can also try over-the-counter herbal supplements like vitex, maca, or ashwagandha. Sometimes progesterone creams or oils can do the trick — but be sure to get one that contains natural progesterone!

If natural remedies aren’t working, your doctor may be able to offer prescription-strength progesterone supplements. If you’re interested in these, we recommend consulting your doctor.

While luteal phase defect can make it more difficult to get pregnant, there are plenty of treatment options you can try!

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“Hormone balance plays a huge role in fertility, and understanding what’s going on with your hormones doesn’t have to be such a mystery.

It’s actually way easier than most people realize.” 

— Amy Beckley, Proov Founder