Luteal Phase Defect: How Does It Affect Pregnancy?

Medically Reviewed by Jabeen Begum, MD on January 22, 2024
5 min read

If it's hard for you to get pregnant or carry your pregnancy to term, one of the possible reasons could be a luteal phase defect, or a defective luteal phase. It's a condition that prevents your uterus lining from thickening as much as it needs to for a pregnancy. However, there's debate about whether luteal phase defect is a direct cause of infertility, and there's no way to test if it is.

The luteal phase is one of the natural stages of your menstrual cycle. It happens right after ovulation (when your ovaries release an egg) and before your period starts. The average luteal phase length is 12-14 days. If you get your period every 28 days, your luteal phase would probably start around day 15. But everyone's cycle is slightly different. A luteal phase of 10-17 days is also considered normal.

The whole point of this menstrual stage is to get your body ready for pregnancy. To do that, hormones in the luteal phase, especially a sex hormone called progesterone, play an important part. Your ovaries produce progesterone, which helps develop the lining of your uterus so a fertilized egg can attach to it. In the luteal phase, cervical mucus thickens and becomes paste-like to keep bacteria from getting inside your uterus in the event of a pregnancy. 

But if there isn't a fertilized egg and you don't get pregnant, your progesterone levels dip. The lining of your uterus sheds, and you have a period.

Some common signs that you're in your luteal phase include:

  • Sore breasts
  • Mood swings
  • Bloating
  • Breaking out (acne)
  • Feeling hungrier or less hungry than usual
  • Thickened vaginal discharge

If your ovaries don't release enough progesterone, or if the lining of your uterus doesn't respond well to this hormone, the lining of your uterus won't grow properly each month. This is called a luteal phase defect. It could make getting or staying pregnant a challenge, but there's still a lot that isn't yet understood about it.

Doctors still don't know what causes a luteal phase defect. Many people diagnosed with it have very short luteal phases that last less than 10 days, so that could play a part. However, many people with short luteal phases are able to get pregnant and carry their baby to term.

Luteal phase defect has been linked to:

If you have a luteal phase defect, you may notice:

  • More frequent periods
  • Spotting (bleeding) between periods
  • A rise in your basal body temperature (your resting temperature) after ovulation

You could also find it a challenge to get or stay pregnant.

It may be hard for your doctor to pinpoint luteal phase defect as the source of a fertility issue. Doctors don't agree on how to diagnose this condition, and there's no single test that can do so. Your doctor will probably suggest lab work that can help figure out what's happening inside your body. For instance, blood tests can check your levels of:

  • Follicle-stimulating hormone (FSH), which causes egg-containing follicles to grow each month
  • Luteinizing hormone (LH), which signals the egg to be released from the follicles
  • Progesterone and estrogen, hormones that help thicken and prepare your uterine lining

A pelvic ultrasound is an imaging test that can help your doctor measure the thickness of the lining of your uterus.

In the past, your doctor may have done a series of endometrial biopsies. They would have removed a small sample of your uterus lining at a specific time of the month and looked at it under a microscope to see if you're "in phase" or not. This is no longer done.

It's important to note that everyone has luteal phase changes from time to time. As an endometrial biopsy can't tell if you're fertile or infertile, it's not recommended as a routine infertility test.

What you do for this condition depends on your overall health and whether or not you're trying to get pregnant. You'll also want treatment for any health issues that can lead to a luteal phase defect.

If you don't want to get pregnant, you may not need any treatment. But if you're trying to have a baby, your doctor may suggest medicines such as:

  • Clomiphene citrate (Clomid). It triggers your ovaries to make more follicles, which release eggs.
  • Human chorionic gonadotropin (hCG). It may help start ovulation and make more progesterone.
  • Progesterone shots, pills, or suppositories. They may be used after ovulation to help the lining of your uterus grow. Progesterone can help some people who get fertility treatments. But no proof taking it after you get pregnant will prevent a miscarriage.

Changes to your daily habits, such as lowering your stress levels or reaching a healthy weight, could also make a difference.

Talk to your doctor about all your treatment options. If you're not using assisted reproduction techniques to get pregnant, there's no proof that treating the luteal phase defect will improve your chances of a successful pregnancy.

If the luteal phase of your menstrual cycle lasts less than 10 days or your ovaries don't make a proper amount of progesterone, you might have a luteal phase defect. There's a lot of debate about how to diagnose and treat this condition. If you have issues getting or staying pregnant, talk to your doctor about your next steps.

Can a luteal phase defect cause infertility?

Luteal phase defects have not been proven to be a direct cause of infertility. But there's no question that proper progesterone levels are crucial for pregnancy. If you're trying to have a baby and tests show that your body isn't making or using progesterone the way it should, your doctor can help figure out why and which treatments could help.