What is a luteal phase?
The luteal phase (LP) of a menstrual cycle is the phase after ovulation and before the start of the period. It is often referred to as the second phase of your cycle.
The Luteal Phase is counted as the number of days post ovulation before the first day of your next period and usually ranges between 10-16 days with the average length being 14 days. Within this time, the follicle which released the egg adapts its purpose (now called a corpus luteum), and starts to produce progesterone to stimulate the lining of your womb to become thicker and more receptive to implantation of a fertilised egg.
Your LP can be longer or shorter.
The longer your phase, the better chance your egg has to embed into your endometrium (the lining of your womb) to begin gestation. It is likely that you have sufficient progesterone to sustain implantation and a healthy pregnancy.
If your LP is shorter, you may have what is known as Luteal Phase Defect. This means that your period will commence before a fertilised egg ever has the chance of settling properly within your uterus. In this instance, it is likely that your body may not be producing enough progesterone.
What is Luteal Phase Defect?
Once you release an egg at the time of your ovulation, the ovarian follicle changes function and turns into the corpus luteum. This is the cell that is responsible for producing the hormone progesterone, which in turn is responsible for maintaining the growth of the endometrial lining. A luteal phase defect refers to a problem with the corpus luteum’s ability to produce enough progesterone to sustain the development of the lining. If your LP ends prematurely, the endometrial lining will break down and you will start your period before an egg has successfully embedded. It is also possible that following a successful implantation, a lack of sufficient progesterone to sustain the endometrium during gestation, can sadly lead to early miscarriage.
Why isn’t my body producing enough progesterone?
There are a few reasons why you might not be producing enough progesterone, particularly if you suffer from any of the following:
• Polycystic Ovarian Syndrome
• Thyroid disorders
• Obesity or Anorexia
Excessive exercise, aging and stress are also contributing factors.
How do I know if I have a short luteal phase?
The best way to find out about the length and quality of your luteal phase is to start charting your cycles. You can do this with ovulation tracking devices, such as Ovusense which record your basal body temperature. It is best to take 2-3 consecutive cycle readings so that you have a better understanding of your own menstrual cycle and your luteal phase.
A typical menstrual cycle can be between 25 to 35 days long with egg development lasting anywhere from 14 to 21 days. The luteal phase can then be monitored post-ovulation to the time you spot or start your period.
How does a short luteal phase affect my chances of conceiving?
It is possible for some women with a short luteal phase of 9-10 days to go on to have healthy pregnancies, but a suboptimal LP can be a problem for others. The longer your LP the better – as implantation usually occurs around day 5/6 post-ovulation. If your endometrium is deficient of progesterone, your womb lining will most likely have already started to break down by then, so you can understand how this can be an issue for women with Luteal Phase Defect or suboptimal LP.
How is Luteal Phase Defect diagnosed?
An endometrial biopsy can detect luteal phase defect. If you are concerned by a short luteal phase, a simple blood test to check Progesterone can help you understand what is happening. A pelvic ultrasound may also help your consultant or GP measure the thickness of the lining of your uterus.
Is there anything I can take or do to help lengthen a short luteal phase?
Depending on your diagnosis, your fertility consultant may suggest a treatment plan to increase your progesterone.