What Are Luteal Phase Defects?

If you’ve gone through fertility treatments in the pursuit of building your family, you may have heard of the term “luteal phase defects”. It’s a term that can come with lots of confusion, which leaves folks feeling lost - how do you treat something that isn’t well understood?

Luteal phase defect, or luteal phase dysfunction, is a condition that prevents the uterine lining from thickening in pregnancy. It is more specific to the luteal phase, where progesterone helps to support the growth and stability of the endometrium for the possibility of fertilization and implantation. A luteal phase, the time frame after ovulation, is usually 11-17 days long but is less than 10 days with a luteal phase defect.

We still aren’t sure what specifically causes luteal phase defects, which can make it frustrating as a person is trying to conceive or go through fertility treatment. It may not even be identified right away if a person isn’t tracking their cycles as intensively, which means more time and money spent on expensive treatments that might not address the root issue.

Other conditions have been linked to luteal phase defects, including eating disorders, endometriosis, hyperprolactinemia, PCOS, thyroid disorders and pituitary gland issues. Conditions where the body’s ability to produce and respond to progesterone impact how long the luteal phase lasts and therefore the potential for implantation. If a condition impacts the ability to ovulate, this can also impact progesterone as the corpus luteum helps produce this hormone and absent ovulation or inadequate hormone production shortens the luteal phase.

Some fertility treatments may inadvertently contribute to luteal phase defects, as some of them alter the body’s own hormone production as a means of controlling if and when ovulation occurs, and therefore the level of progesterone that may be produced after ovulation. This doesn’t mean that fertility treatments cause these defects, but they can be important to watch for throughout the treatment process. A great specialist can modify treatments to the person and make changes based on the patient’s response and symptoms. Luteal phase defects have not been found to be a direct cause of infertility, but they are important to assess and treat.

While not a medical condition per se, high stress levels have been associated with luteal phase defects. This may be more specific to preventing ovulation, where the body reads its environment as unsafe to become pregnant and therefore stops the hormonal communications that allow for ovulation to happen.

There have also been some links to various nutrition and lifestyle considerations that may impact the luteal phase. Extreme or excess exercise, and extreme weight changes, have been associated with luteal phase defects. Again, this may be related to negative impacts on hormone production to support both ovulation and uterine lining growth. This is often why the recommendation to eat in a restrictive manner in attempts to become pregnant can backfire - bodies of all sizes may become pregnant, and being in a larger body does not guarantee infertility or poor pregnancy outcomes. Weight stigma in prenatal settings is more strongly associated with health complications in pregnancy than weight itself, especially for Black and Indigenous people of colour (BIPOC).

And we can’t leave out nicotine use as a risk factor for luteal phase defects. Nicotine use impacts circulation through the body, including to the reproductive organs, and can reduce blood flow that is needed for tissue growth and function. Nicotine also has a significant cancer risk attached to it, so reducing use or quitting entirely is essential when trying to conceive.

Symptoms of a luteal phase defect include more frequent periods, as cycles become shorter, spotting between periods and challenges both getting and staying pregnant. A person may experience recurrent miscarriages early in their pregnancy, which is both physically and emotionally taxing.

As part of assessing for luteal phase defects, a variety of hormones can be measured in blood, along with other testing methods to assess reproductive tissue health. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are measured to assess the hypothalamic-pituitary ovarian axis, which sends messages from the brain to the ovary to trigger ovulation. Progesterone and estrogen are also measured to assess hormone production that impacts ovulation and the length of the luteal phase. Some folks may have a pelvic ultrasound to view the structures of the reproductive system and identify any issues, or endometrial biopsies to check the thickness of the uterine lining.

Treatment is different for everyone - Clomid is a medication that can trigger ovulation if a person is found to not be able to do it on their own. hCG is another option for starting ovulation and supporting progesterone production, and may be used throughout the initial weeks of pregnancy. Progesterone medications can also be an option, especially if there are no identified issues with ovulation and all other tests come back normal aside from a short luteal phase.

From a lifestyle perspective, addressing exercise, managing stress levels and ensuring that enough energy is consumed is also critical. A body needs to be well-fueled for healthy pregnancies and cycles, and this may involve an element of weight restoration, especially if a person has had significant weight loss. Working with a dietitian who takes a non-diet and weight-inclusive approach is an advantage, because they not only help address your nutrition needs for fertility, but they support you in building a healthy relationship with food that will continue well beyond pregnancy and postpartum too.