If you’re tracking your menstrual cycles or focusing on fertility, it’s helpful to understand the luteal phase. A defective luteal phase is a common cause of fertility problems.
Here’s what you should know about this phase of the menstrual cycle, including:
- When it happens.
- Symptoms you may have during the luteal phase.
- How long it lasts.
- Signs of a luteal phase defect.
What Are the Phases of the Menstrual Cycle?
A woman’s menstrual cycle typically lasts about 28 days. Each cycle, hormonal changes trigger your body to go through four phases to prepare for a pregnancy:
- Menstruation (menstrual period) — If you’re not pregnant, your body sheds the lining of your uterus through your vagina during this phase. A new menstrual cycle begins on the day your period starts. Menstruation lasts between four and eight days for most women but can vary by a few days.
- Follicular phase — This phase starts during your period. Estrogen causes the lining of your uterus to gradually thicken and prepare for pregnancy, while follicle-stimulating hormone prepares an egg for ovulation. The follicular phase typically lasts 13 or 14 days.
- Ovulatory phase (ovulation) — During this short phase, luteinizing hormone surges, causing your ovary to release an egg. The process of releasing an egg, ovulation, occurs around day 14 of your menstrual cycle and lasts only 16 to 32 hours. A sperm can fertilize your egg for about 12 hours after ovulation.
- Luteal phase — This final phase lasts from about day 15 to day 28, when the egg travels from your ovary to your uterus. A fertilized egg attaches itself to the wall of your uterus and starts to grow, signaling a pregnancy. If the egg isn’t fertilized, estrogen and progesterone levels drop, and you shed the egg and uterine lining during your period.
How Does the Luteal Phase Affect Pregnancy?
The luteal phase is crucial for fertility because it’s when your uterus prepares for pregnancy. The hormones estrogen and progesterone increase, causing the uterine lining to thicken with nutrients to nourish an embryo. Your cervical mucus also thickens and becomes sticky, which keeps bacteria out of your uterus in case you’re pregnant.
Conception can occur right after ovulation, at the start of the luteal phase, as long as your uterus and hormones are ready. When a fertilized egg implants itself in the uterine lining, your body must continue to produce enough progesterone to help it grow.
What Is a Luteal Phase Defect?
A normal luteal phase typically lasts 11 to 17 days. That length of time is key to your body making enough progesterone to prepare your uterus.
But a luteal phase lasting less than 10 days may not allow your body to make enough progesterone, causing a hormone imbalance. In some cases, even with progesterone, your uterine lining doesn’t thicken as it should to support a pregnancy.
Doctors refer to this as a luteal phase defect or luteal phase deficiency. It’s a common cause of fertility problems, early pregnancy loss, or repeat miscarriages.
A luteal phase defect can happen for various reasons, including:
- Aging.
- Eating disorders.
- Excessive exercise.
- Health conditions like thyroid disease, polycystic ovarian syndrome (PCOS), or endometriosis.
- Significant weight loss.
- Stress.
If your doctor suspects a luteal phase defect, they may run blood tests to check your progesterone or other hormone levels.
They may also ask you to track your menstrual cycles for a few months. Watching for certain signs and symptoms each cycle can help determine when your luteal phase happens and how long it lasts.
What Are the Symptoms of the Luteal Phase?
A normal menstrual cycle lasts 24 to 38 days, although many people have irregular cycles. If your cycle is shorter or longer than average, you may wonder how to tell when you’re in the luteal phase.
A menstrual cycle tracking app can help. It calculates when you can expect the luteal phase of your cycle based on the information and symptoms you share. You can also track these symptoms in a notebook without an app:
- Basal body temperature — Take your temperature with a digital thermometer as soon as you wake up, before you get out of bed. You’ll notice it changes during your cycle after you enter the luteal phase. Right after you ovulate, your basal body temperature will increase by about 0.5 F.
- Cervical mucus — During ovulation, vaginal discharge (mucus from your cervix) is thin, slippery, and stretchy like an egg white. When you start your luteal phase, cervical mucus becomes thick and sticky.
- Mood and appetite — You’re more likely to have mood changes like anxiety or irritability, or mood swings during this phase. You may also notice increased hunger or cravings for foods like chocolate or sweets.
- Physical symptoms — These may include breast tenderness, bloating, or acne breakouts.
Hormone changes, especially an increase in progesterone, cause these changes during the luteal phase.
Luteal phase defect symptoms
You can estimate the length of your luteal phase by counting the number of days between the day you ovulate and the day you get your period. If it’s 10 or less, you may have a luteal phase defect.
Other symptoms of a defective luteal phase may include:
- Difficulty getting pregnant.
- Periods that come every 21 days or less.
- A slow, rather than sudden, rise in basal body temperature.
- Spotting between periods.
If you notice these symptoms, discuss them with your doctor.
How Do You Treat a Luteal Phase Defect?
If pregnancy is your goal, you should know that many women with a short luteal phase have successful pregnancies and healthy babies.
Your doctor may treat a luteal phase defect with:
- Medication to increase progesterone production after you ovulate.
- Medication to stimulate follicle and egg growth.
- Progesterone supplements starting a few days after ovulation. Your doctor might recommend a progesterone pill, shot, or vaginal suppository to increase progesterone levels.
These luteal phase defect natural treatments are also essential:
- Eating a healthy diet that provides enough calories and nutrients to support pregnancy.
- Getting regular but moderate exercise most days of the week, like walking, Pilates, or swimming for about 45 minutes.
- Managing stress with yoga, meditation, or talk therapy.
- Managing underlying health conditions.
- Sleeping seven to nine hours each night.
- Take prenatal vitamins if you’re trying to conceive. They provide the nutrients you need for hormone health before, during, and after conception.