Luteal Phase Defect: How it Affects Your Chances for Pregnancy

If you’re trying to become pregnant and find yourself taking a while to conceive, or if you became pregnant and suffered one or more first trimester miscarriages, you may be wondering if you have a luteal phase defect (LPD). 

This is a good question to ask. Luteal phase defects are thought to be a common cause of problems becoming pregnant. However, their diagnosis and relationship to fertility remain controversial. 

Here’s what we know:

• A normal luteal phase is necessary for successful implantation and growth of the embryo. 
• We also know that assisted reproduction techniques like IVF cause luteal phase defects. Ovarian stimulation interferes with progesterone production during the luteal phase.
• Women undergoing ovarian stimulation are therefore routinely treated with supplemental progesterone. This practice dramatically improves ongoing pregnancy and live birth rates following IVF. 

What’s controversial is how to test for and diagnose LPD in women trying to conceive naturally. Doctors used to test progesterone levels or take a biopsy of the uterine lining. But these tests are no longer considered accurate. The inability to diagnose LPD has greatly hindered research on how LPD contributes to infertility in natural (unassisted) cycles. 

Of course, just because we cannot test for something does not imply it is not a problem. Many clinicians will therefore treat LPD, especially since most the common treatments, like supplemental progesterone, are well-studied and considered low risk.

What happens during a normal luteal phase?

The luteal phase starts on the day of ovulation and lasts until the first day of your period. This is when your uterine lining (endometrium) thickens to prepare for a possible pregnancy.

Ovulation occurs when the dominant follicle (or sac) in your ovaries releases an egg. The egg then travels down the fallopian tube to become fertilized. 

After releasing the egg, the remaining follicular cells form a structure on the ovary known as the corpus luteum. The corpus luteum then begins releasing hormones, mainly progesterone and estrogen. These hormones cause your uterine lining (endometrium) to thicken and to undergo other changes to prepare for implantation.

If implantation occurs, the corpus luteum continues to secrete progesterone to maintain the pregnancy. A corpus luteum is required to sustain pregnancy for the first 7-9 weeks, at which point the placenta takes over. 

What is a luteal phase defect (LPD)?

A luteal phase defect occurs when your uterine lining fails to adequately prepare for pregnancy. It can lead to failed implantation or early miscarriage. Often, this arises as a luteal phase that is shorter than normal. But sometimes progesterone levels are low despite the luteal phase being a normal length.

A normal luteal phase lasts anywhere from 11-17 days, with most between 12-14 days. Luteal phases less than 10 days are too short to allow for successful implantation and growth of a fertilized egg.

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

Cycle Tracking

The length of your menstrual cycle alone cannot tell you whether you have a luteal phase defect. If, for example, you have a long pre-ovulation (follicular) phase followed by a short luteal phase, the long time to ovulation masks the short luteal phase. 

To determine your luteal phase length, count the number of days between ovulation and your period. Start counting on the day of ovulation and stop counting on the first day of your menstrual period. 

(For example, if you ovulated on cycle day 14, and got your period on cycle day 28, your luteal phase was 14 days long.)

You’ll also have to track this for more than one cycle. A single menstrual cycle cannot tell you if you have a luteal phase defect. Many women have a short luteal phase from time to time; this is normal and unlikely to affect your fertility. 

However, a luteal phase consistently shorter than 10 days can make it harder for you to become—or to stay—pregnant. 

Clinical Tests 

Doctors used to diagnose a luteal phase defect by measuring progesterone in the blood or by taking a biopsy (sample) of the uterine lining. Neither of these approaches are currently considered accurate. Progesterone levels vary dramatically from hour to hour (up to 800% within 90 minutes), and biopsies of the uterine lining do not reliably distinguish women with normal cycles from those with a luteal phase defect.

Other possible symptoms of a luteal phase defect include: 

• Spotting between periods
• Miscarriage, especially early or recurrent miscarriages
• Difficulty becoming pregnant
• Short menstrual cycles

What causes a luteal phase defect? 

A luteal phase defect occurs when your ovaries fail to produce enough progesterone or when your uterine lining fails to respond to normal levels of progesterone. 

Assisted reproductive techniques, such as IVF, that use hormones to stimulate egg production cause luteal phase defects. Women undergoing ovarian stimulation therefore take progesterone to ensure the proper development and maintenance of the uterine lining. 

Certain health conditions and other factors can raise your risk of a luteal phase defect. These include: 

• Obesity 
• Excessive exercise (more info on how to exercise without lowering your fertility)
• Polycystic Ovarian Syndrome (PCOS)
• Stress
• Breastfeeding 
• Thyroid problems 
• Hyperprolactinemia 

Can stress cause a short luteal phase?

One of the most irritating and obnoxious responses to disclosing your problems becoming pregnant is to be told, “just relax. don’t stress.” 

That said, stress does seem to play a role in luteal phase defects, especially if the stress is severe or prolonged. 

Stress in humans is difficult to study experimentally. In monkeys, researchers have shown that severe, prolonged stress lowers progesterone levels during the luteal phase. And at least one study suggests the same may be true in humans. Among women in rural Malaysia, higher urinary cortisol (a stress hormone) correlated with lower progesterone levels during their luteal phase. However, other studies have not found a link between stress and luteal phase progesterone. 

Some stress is unavoidable. How it affects your body comes down to not just how severe, prolonged, or frequent it is, but also how well you can cope or find calm in its midst.

Can breastfeeding cause a short luteal phase? 

Many women who are breastfeeding experience short luteal phases. Things tend to return to normal 1-2 cycles after weaning. 

There are a couple of reasons for this. First, breastfeeding releases prolactin, a hormone that can interfere with ovulation and proper functioning of the corpus luteum. Second, breastfeeding requires a lot of calories, which can disrupt the menstrual cycle by creating a negative energy balance (when you expend more energy than you consume). 

Birth, even when not followed by breastfeeding, also disrupts the luteal phase for your first few menstrual cycles.  

How is a luteal phase defect treated?

Certain health conditions, like thyroid problems, can cause luteal phase defects. Your doctor will evaluate you for these potential underlying conditions. If no obvious health culprit is identified, treatment aims instead to improve hormone levels during the luteal phase. 

There are a couple of popular approaches: 

1. Stimulate egg development with clomiphene citrate (clomid), letrozole, or human menopausal gonadotropins (HMG) to improve the quality of the dominant follicle and thus the corpus luteum.
2. Directly stimulate uterine lining growth with progesterone and/or HCG during the luteal phase.

Because of the difficulty of diagnosing LPD, it is unclear whether these treatments help women who have trouble becoming pregnant. But for women who have suffered multiple miscarriages, supplemental progesterone does seem to lower their chances of a subsequent miscarriage. 

Natural treatments for Luteal Phase Defect?

If you think you might have a luteal phase defect, the best course of action is to seek medical care. Your doctor can tell you if you have an underlying condition that might be affecting your luteal phase. 

A few small, low-quality studies have suggested that vitamin C might help improve progesterone levels in women with luteal phase defects. While the value of supplement vitamin C is unclear, eating a varied diet rich in fruits and vegetables is always a good idea. 

Some other natural care providers suggest using an over the counter progesterone cream. But caution is warranted. We do not know the value (or risks) of using these OTC creams while trying to conceive. 

Amy Kiefer, PhD

Amy Kiefer is a researcher by training and earned her Ph.D. from the University of Michigan. She currently lives in the Bay Area with her husband and three children where she writes about fertility, pregnancy, and breastfeeding. Check out her blog, expectingscience.com.