Luteal Phase – What It Is and It’s Relation to Pregnancy

A menstrual cycle consists of 3 phases namely ovulatory, luteal and follicular. Each phase of the menstrual cycle has its own importance in fertilizing the ovum and making you pregnant. If you aren’t pregnant, it also sheds the unused endometrial lining at the termination of the cycle. This article is about the Luteal phase and its relation to pregnancy.

What is Luteal Phase?

The period between ovulation and the beginning of the next menstrual cycle is called Luteal Phase. The follicle gets converted to corpus leteum during this phase. Corpus Leteum is the structure which produces high amounts of luteal phase progesterone and some oestrogen also. These luteal phase hormones play an important role in pregnancy.

If you have a normal menstrual cycle of about 25-28 days, the luteal phase will last for about 12-14 days. But if you have a menstrual cycle lesser than 25 days, the luteal phase can be shorter.

But can you get pregnant during the luteal phase? Yes, you can. Since the luteal phase is after ovulation, you have a very real chance of getting pregnant.

Why is Luteal Phase Important for Pregnancy?

The luteal phase is the period between ovulation and menstruation. Therefore, the health and length of luteal phase will speak a lot regarding your fertility.

1. Impact of the Luteal Phase’s Length On Pregnancy?

If your period of luteal phase is less than ten days, then you may find it hard to become pregnant. The reason behind this is that if your corpus leteum weakens and dies in 9 days, ceasing the luteal phase hormones production, then your uterus starts shredding instantaneously, leaving no time for the fertilized ovum to move to the fallopian tube to the ovary and get implanted to the uterus lining.

If your luteal phase is short, you will not get pregnant even if the ovum gets fertilized because you will get your period before the embryo can stick to the uterus lining.

2. Impact of The Luteal Phase’s Health On Pregnancy?

Sometimes, even if the duration of the Luteal phase is normal, your body produces less amount of progesterone during this phase. This is also a problem. A sufficient quantity of progesterone is essential to ensure the healthy thickness of the uterus lining. Low amount of progesterone results in a uterus lining that is not healthy enough to sustain a pregnancy.

Therefore, it is important to have a Luteal Phase that is of normal length and is healthy as well.

How to Calculate Luteal Phase of a Menstrual Cycle?

Here are some ways to calculate the length of Luteal Phase:

• A hormone-specific blood test can determine the accurate length of your luteal phase of menstrual cycle.
• You can also track your menstrual cycle for approximately 6 months. Observe the patterns of your phases of the menstrual cycle to calculate an approximate length of the luteal phase.
• Basal Body Temperature (BBT) Charting: The BBT of your body increases during ovulation and stays high until the onset of your upcoming period. Track the temperature from the starting of the menstrual cycle and observe the rise in BBT. The rise in body temperature is a solid confirmation that you are ovulating.

Formula to calculate the ovulation time during luteal phase:

• Day of Ovulation= Length of the Menstrual cycle – Length of Luteal Phase

For instance, assume that for a menstruation cycle that lasts for 29 days, the luteal phase lasts up to 15 days. Assigning these values in the formula,

• Day of Ovulation = 29 (Length of the Menstrual cycle) – 15 (Length of Luteal Phase)
• Day of Ovulation=14

It implies that the fourteenth day of the menstrual cycle is the day your ovulation occurs.

A prediction kit or calculator for ovulation can also be used to know the day of ovulation and hence the luteal phase.

Body Changes in Luteal Phase

During the Luteal Phase, the upsurge in progesterone levels can result in the following body changes:

• Mood swings
• Tiredness
• Tenderness of nipples and breasts
• Bloating
• Anxiety
• Fluid retention

These changes are bound to happen and do not lower your likelihood of getting pregnant.

What Causes a Short Luteal Phase?

When your body doesn’t produce sufficient progesterone, your luteal phase might end early. The following reasons might be responsible for not producing enough progesterone:

• Thyroid disorders
• PCOS
• Obesity
• Excessive exercise
• Anorexia (and milder forms of restrictive eating)
• Stress
• Ageing

How Do You Know That Your Luteal Phase is Short?

You can know that your luteal phase is short by tracking your menstrual cycle. Count the number of days between ovulation and the onset of your next period this will give you the length of the luteal phase.

If your luteal phase lasts for 12 or more days, it is normal. But if your luteal phase lasts less than 10 days, you have low progesterone level. This means that your luteal phase is short.

How Can You Test Your Progesterone Level?

The luteal phase progesterone levels are generally higher than other phases of menstrual cycle. The progesterone level should be tested when it is highest, i.e. in the middle of the luteal phase. The middle of the luteal phase is on the 21^st day of a normal 28-day menstrual cycle.

But it is not necessary that you have a typical 28-day menstrual cycle. If you have a 34-day menstrual cycle, with an ovulation on the 22^nd day. then if you can your progesterone level tested on day 21, the results might show a very low level of progesterone. But if you test it on the 28^th day, your progesterone level may be normal. Hence, if you want to know when to ovulate and the length of your luteal phase, tell your doctor about the right time to test your progesterone levels.

How Can You Increase the Luteal Phase?

Taking the following supplements might help to lengthen the luteal phase:

• Vitamin C- It increases fertility in some case where women have short luteal phases.
• Progesterone supplementation or cream- Progesterone cream can increase your progesterone levels but you consult your doctor before doing so.

What is a Luteal Phase Defect?

Luteal Phase defect or Luteal insufficiency can be termed as the deficient release of progesterone all through the luteal phase. The insufficiency of progesterone will avoid the thickening of uterus lining that might result in improper embryo plantation. Hence, it reduces the chances of continuing with the pregnancy. However, it is not yet confirmed if luteal phase defect is a reason for infertility.

The Luteal Phase Defect can lead to the following problems:

• Improper working of corpus luteum which results in the lesser production of estradiol and progesterone.
• The incapability of the uterus lining to react to the normal levels of estradiol and progesterone.

1. Cause of Luteal Phase Defect

The luteal phase defect could happen due to the following reasons:

• Defect in the ovulated egg
• Breakdown of corpus luteum
• Unruptured follicle
• Thyroid disorders
• Over-exercise
• Anorexia
• Endometriosis
• Polycystic ovary syndrome
• Obesity
• Hyperprolactinemia

2. Symptoms of Luteal Phase Defect

The symptoms of luteal phase defect are as follows:

• Miscarriages
• Spotting in between periods
• Menstrual cycles way earlier than normal

3. How is the diagnosis of Luteal Phase Defect done

Luteal Phase defect can be diagnosed by getting the following tests done:

• Blood tests  

It checks the level of

1. Progesterone that helps in the thickening of the uterus lining.
2. Follicle simulating hormone that regulates the ovarian function.
3. Luteinizing hormone that triggers ovulation.

• Ultrasound

It helps to find the thickness of the uterus lining. An ultrasound scan can help detect the functioning of the reproductive organs, i.e. uterus, ovaries, cervix and fallopian tube.

• Endometrial Biopsy

Get this done at least one or two days before the start of periods. A small sample of your endometrial lining is procured and examined under a microscope to check the lining thickness.

4. Treatment options for Luteal Phase Defect

The treatment of the luteal phase defect depends on the main underlying causes.

• Human Chorionic Gonadotropin: It releases progesterone and triggers ovulation. During this process, the hCG level is given in a single dosage of 10,000 IU or two dosages of 5,000 IU given once in 2 weeks to extend the luteal phase.

• Clomiphene Citrate: These are also called human menopausal gonadotropins. These help in stimulating the ovaries to produce more follicles which releases more eggs.

• Suppositories: Crinone, a vaginal gel, is used vaginally three times a day. The gel holds a progesterone dosage of 90 mg.

• Pill Treatment: Prometrium oral progesterone medicines are administered at a 200 mg dosage a day.

• Injections: Intramuscular progesterone is administered with a dose of 25-50 mg per day. The injection uses crystalline and odourless progesterone powder is dissolved in sesame oil.

The luteal phase that lasts around 14 days is the time when the female body prepares the womb for the fertilized ovum. You should have a luteal phase of both sufficient length and health to sustain a pregnancy. You can consult a doctor for mid luteal phase progesterone test to check if everything is normal.

Also Read: LH Surge