If the relationship between the luteal phase and fertility had a FaceBook status, it would be 'it's complicated'.  Luteal phase defect was a condition first described in 1949 and despite the primary mention being almost 70 years ago, the understanding and research on this issue is still incomplete and it remains a controversial topic.  So what is a luteal phase defect?  Is it really a problem and if so how can you treat it? Spoiler alert - natural treatments will be needed as the NHS are dismissive (based on research) of treating this particular complaint.

What is meant by a luteal phase defect?

Short luteal phase - The Preggers Kitchen luteal phase defect

The luteal phase of the menstrual cycle is the phase after ovulation and before the start of the period.  If you are charting your menstrual cycles then this will consist of the phase post ovulation, usually calculated from the first day on which your basal body temperatures is above the cover line until the day before your period.  If this is total gobbledygook to you and I lost you at “charting”, then you may be interested in reading about the basics here.

Now for a canter through some research: Luteal Phase Defect may show up on a fertility chart as too few high temperatures post ovulation.  Spotting before the beginning of your period may also be a sign that progesterone levels are lower than desirable and may also indicate an issue with the luteal phase.  

Research indicates that the normal luteal phase length from ovulation to menses ranges from 11 to 17 days with most luteal phases lasting 12 to 14 days.  Research has used varying definitions of a short luteal phase: fewer than  9 days,10 days, or 11 days.  If the luteal phase is insufficient then there is a strong change that the corpus luteum (the follicle that releases the egg) did not form properly that month or sufficiently mature before ovulation. This in turn means that your body does not produce sufficient progesterone to sustain a pregnancy. 

A common definition of inadequate luteal function is progesterone levels that do not reach 16 nmol/liter for at least 5 days.  Studies have found that all cycles with a luteal phase of fewer than 9 days were abnormal, and that 74%, 22% and 2% respectively of cycles with luteal phases of 10, 11 and 12 days were also abnormal, which would strongly suggest that a luteal phase of 12 days or longer would be the most fertile.

To put this into my context (not that it is all about me, so please excuse the self-indulgence), for the first year of charting my cycles when trying to conceive (in 2015) my luteal phases ranged from 8 to 10 days. The research would indicate that for an entire year between three quarters to all of my cycles were abnormal.  Well that’s just spiffing isn’t it. That's no good for baby production, pull yourself together you useless corpus luteums.

How common is a short luteal phase?

The short answer is 'not very', which makes me ‘special’. Not in a warm and fuzzy feeling way, more in an infertile way. It is safe to say that short luteal phases are rare with only 3.5 percent of women who are evaluated for infertility are reported to have luteal phase defects.  It is more common in younger women (37% of menstrual cycles in women aged 18-20 years, as compared with only 9 percent of cycles in women aged 35-39 years with temperature elevations lasting fewer than 10 days).  Different studies have shown that 15% of cycles of adult women had luteal phases shorter than 11 days, 3.2% of women in the multinational World Health Organisation study had luteal phases of less than 8 days and 2.1% of women in a smaller clinical study had short luteal phases. Around 6% of women have insufficient progesterone production; however, the definition of insufficiency was based on the 95th percentile of progesterone production. 

Does having a short luteal phase impact on fertility?

In theory a luteal phase defect may occur if there is insufficient progesterone produced to properly develop and sustain the lining of the womb for implantation of a fertilised egg. It is recognised by the Practice Committee of the American Society for Reproductive Medicine that it is plausible that a short luteal phase could be a cause of infertility or pregnancy failure, given the importance of ovarian progesterone production to implantation of the embryo and early pregnancy. However, confusingly other research has shown that having a short luteal phase of fewer than 11 days does not have a correlation with unexplained infertility.  The murky picture is further dirtied by plenty more conflicting evidence on luteal phase length and fertility.  A good summary of the conflicting evidence, issues and difficulties with testing for and treating supposed luteal phase deficiency has been published by the American Society for Reproductive Medicine, which goes on to conclude that:

'Although there appears to be an association with infertility, it has not been established that persistent LPD [luteal phase defect] is a cause of infertility'.

What is clear from the research is that between 12 to 16 days is definitely considered to be adequate and removes you from the tedious and frustrating debate about the existence of luteal phase defect.

Will a short luteal phase be recognised as an issue by the NHS?

Nope.  Not a chance.  Definitely not.  Don't even go there.    

In my experience, GPs and other healthcare providers in the UK are entirely dismissive of the concept of luteal phase defect.  This is likely to be because the National Institute for Health and Care Excellence (NICE), which provides guidance, advice, quality standards and information services for the NHS, is dismissive of such a concept.  Although GPs often recommend as part of fertility checks a blood test to measure serum progesterone in the mid-luteal phase (inaccurately known as the 21 day progesterone test), the purpose is to confirm ovulation rather than to explore luteal phase defect.  NICE guidance on Fertility Problems: assessment and treatment guides the NHS that: 

'Women should not be offered an endometrial biopsy to evaluate the luteal phase as part of the investigation of fertility problems because there is no evidence that medical treatment of luteal phase defect improves pregnancy rates.'

The sentiment behind this guidance somewhat confuses me as it does not say that there is no evidence that luteal phase defect is an issue for fertility.  What is says is that there evidence has not shown there to be an effective treatment for luteal phase defect.  These are two different issues, although I appreciate why it may not be recommended to undertake diagnostic tests for a medical issue for which there is no effective treatment.  

Although since 2013 NICE has recommended that the NHS offer women progesterone for luteal phase support after IVF treatment (but not for unassisted pregnancies).  

What can be done to fix a short luteal phase?

Many people take progesterone as a means of extending and supporting the luteal phase.  A nice little suppository stuck up the butt or the vagina which leaks (baby making is so romantic at times), but as progesterone is not something commonly offered by doctors in the UK, outside of artificial reproductive cycles, and my attempts to regulate my cycle are focused around natural treatments, I have not supplemented with progesterone but instead have tried to coax my body to produce and manage progesterone effectively using the following strategies:

Fertility Blend supplementation

Supplementation has been shown to improve levels of progesterone and subsequently, pregnancy rates.  A study by Stanford University published in the Journal of Reproductive medicine considered one specific supplement, Fertility Blend.  It was a small study with only 30 infertile women taking part, but 27% in the Fertility Blend group fell pregnant within 3 months in comparison to 0% in the control group.  After the trial ended one of the control group began taking the supplement and also fell pregnant.  The study found that the mean progesterone levels in the Fertility Blend increased, demonstrating the importance of progesterone in pregnancy.  The fact that I have never taken Fertility Blend now appears to be a huge error and one I plan to rectify pronto.

Vitamin C supplementation

Vitamin C supplements for luteal phase defect - The Preggers Kitchen

A study by Sami R. Al-Katib showed that a daily 1500 mg (1.5 grams) vitamin C supplementation significantly increasing the thickness of the endometrium (lining of the womb) within 1-2 menstrual cycles and the same effect was shown in both infertile and fertile women.  Parity at last.  And a change within 1 cycle? Who doesn't love a quick result when it comes to a cycle improvement, especially as most changes are slow burners. The sample size for this study was small, only 30 women which seems to be the magic number, and 1.5 grams of vitamin C taken orally is pretty large.  When vitamin C is consumed orally it can only be taken to bowel tolerance (i.e. when you need to put on your Pooey Pants it is time to cut back). 

Al-Katib referenced further research which showed that luteal phase defects decreased about 53% in the vitamin C supplemented group while the defects spontaneously improved about 22% in non-supplemented group.  The longer luteal phases may be because it encourages more mature eggs and better functioning follicles, as the concentration of ascorbic acid is higher in mature ovarian follicles than immature.  Or it could be that the vitamin C increases progesterone production, which helps to sustain the luteal phase.  Al-Katib discussed another study that showed that three months of vitamin C supplementation resulted in a trend towards an increase in mean mid-luteal progesterone concentrations and a significant increase in the number of days with higher basal body temperatures. After five months of supplementation, the pregnancy rates were significantly higher in the supplemented group.  

Where should one go for some vitamin C?  The main source of vitamin C is found in fruits and vegetables.  Of course, it is always veg isn't it?  Whatever fertility subject is researched, all roads lead back to veg.  An article on 12 Foods that have more vitamin C than oranges confirms everyone's worst fear.  Slipped in at number 5, there she is, the curly haired nutritional powerhouse of disgustingness: kale.    

Now I do not advocate for supplementation instead of a varied and heathy diet, but it can’t hurt to supplement in addition, right? Once that delightful kale smoothie has ruined both your morning and your breath it can’t hurt to make sure that your vitamin C levels are in tip top condition. Vitamin C supplementation is an additional means of getting it down you but with a milder taste, especially if you are planning on heading to the lofty heights of hitting the big numbers (1.5 grams).  I have previously used Solaray's Super Bio C Buffered and currently use Bio Care vitamin C powder.

Vitamin B6 supplementation

Seed cycling

Saffron extract

Estrogen detoxification

Stress management and good digestion

These two remain fundamentally important no matter what other tricks we try, tacks we take, roads we travel down to coax more progesterone production from the existence of that stubborn little follicle.  The stress hormone cortisol rides roughshod over the delicate balance of the body's reproductive hormones, such as progesterone.  So if you are indulging in all the above activities but engaging in life as a Class A Stress Cadet, then things are unlikely to improve.  The same goes for digestive health, as without a good healthy gut your body may not absorb the wonderfully nutritious food and vitamins you are plying it with to assist your cycles, resulting in the only one to benefit being Amazon from all the vitamins you bought, which makes for a depressing world. For more tips on stress management visit here and if it is a dodgy tummy that plagues you there are more tips and tricks here.