The pee-on-the-stick ovulation prediction kits are one of the better known methods for finding your fertile window.  The aim is to detect the surge of a hormone known as Lutenizing Hormone (LH) which should spike just before ovulation. This is great in theory and does work well for some people. However, the research taking a look at the accuracy of these throws up some elements that anyone using them to try for a baby needs to know about. Particularly anyone who has been struggling with conception. Worse case they can lull people into a false sense of security and risk issues being picked up. 

Below are the ten (lesser known) things you need to know if you’re using them for your own conception journey. 

How they ‘should’ work to detect ovulation: 

In order to get ovulation we need a dominant follicle (immature egg) to grow to the ‘right size’ and then to be released for potential fertilisation. 

The test kits help to predict this crucial moment using a few clever things that happen in the body in the lead up:

• Before ovulation, the dominant follicle releases a potent form of estrogen known as estradiol.
• When this level is high enough it triggers the pituitary gland to release LH into the blood stream. This is the hormone that the test kits pick up.
• It is this surge in LH that should then trigger ovulation around 24-48hrs later. So far so good…. 

This is brilliant when it works as it gives you the signal before ovulation occurs. That’s what we want. When it comes to timing sex for conception – early is most certainly better than late. 

Here are 10 things to know about pee-on-a-stick LH ovulation kits:

Whilst they are super useful when they work, LH test kits do not work for everyone. They can be misleading, cause anxiety or even lull us into a false sense of security preventing issues from being picked up. So, if you’re using them here are some things to know: 

One: it’s the estrogen that triggers an LH surge which the kits pick up: this is important to know if you have hormonal imbalance…. 

For ovulation to happen (and for kits to be able to pick up the signals) your hormones need to be working as they should. That is sadly not the case for everyone! 

In fact, the surge in LH that you need to trigger ovulation actually happens as estrogen (from the dominant follicle to be released) peaks. The research suggests estrogen will peak to a level of around 200pg/ml for 50 hours before. It is this that triggers LH to be released.

So, if you have imbalances in your estrogen (click here for more) you may have dysfunction when it comes to LH and it’s surge. PCOS is another common reason why these kits may not work and many people are unaware they have it. This can lead to a lot of wasted time. Click here for much more. 

Two: timing: the gap between LH surge and ovulation… 

The absolute best way when it comes to timing sex for conception is to have sex every 2-3 days through your cycle. However, with our modern lifestyle that isn’t always practical!

So, when you’re using an LH test kit here are some stats to bear in mind which may help once you’ve registered a positive LH surge: 

The average time after a positive urinary LH test to ovulation is estimated to be 20 hours.

Of course this is an average and people will differ… 

However worth bearing in mind: ‘the clinical pregnancy rate after a single incident of intercourse is highest from a point two days before ovulation to the day of ovulation.’ 

So: it is definitely better to be early rather than late when it comes to timing sex for conception. Sperm can survive for 3-5 days internally so better to go too early than too late. A positive LH reading is a green light. 

Three: the peak…. 

Typically from the highest point of LH; ovulation will happen 10-12hrs later. Some kits will measure the exact amount of LH you have in your urine, so if you want to get very technical there you have it! 

Four: when do you test your LH levels? 

Turns out – LH (on average) is a bit of a night owl.

One study looked at the average timing for the start of the LH peak and actually found that it typically started during the night.

• 37% of those studied started the rise between midnight and 4am
• 48% between 4am to 8am.

This may be why some manufacturers of test kits recommend testing first morning urine. This is also when your urine tends to be most concentrated. So, if you want to get specific, best to test first morning urine. 

Five: LH surge does not always = ovulation: 

This is where we start to get into issues. Most people assume that registering a positive LH surge is a guaranteed test for ovulation. However, the science suggests this is not always the case. According to one paper:

‘there are still some indications that LH surge may not signify true ovulation’ 

Six: not all LH surges look the same: 

Research suggests that LH surges are in fact extremely variable person to person. With three broad types:

1. Rapid on-set (ie peak within a day) around 43%
2. Biphasic (ie. peaks in two waves) (44%)
3. Rise and then plateau (14%)

So not everyone looks the same which is why it can be confusing to interpret. Again, another reason why these tests shouldn’t necessarily be solely relied upon. 

Seven: LH test kits are typically far less effective if you are having fertility issues: 

One study demonstrated that women suffering with infertility often had premature LH surges that did not trigger ovulation. This was detected in 46% of cycles of women struggling with fertility issues. Once again, if you’re concerned about the readings/that you may not be ovulating speak to your doctor asap. This makes sense as when it comes to female infertility, research shows that the majority of the time ovulatory dysfunction is a cause.

Eight: PCOS and other hormonal imbalances are major reasons why this test does not work for some women:

Polycystic Ovarian Syndrome (PCOS) is a hormonal imbalance at it’s heart. It often comes hand in hand with lack of ovulation and usually because hormones are out of balance. One of the ways this manifests is no LH surge or an LH surge that is atypical and fails to trigger ovulation. Once again, chat to your doctor about further investigation. 

Nine: you can have an LH surge and have no ovulation: 

This is known as ‘lutenized unruptured follicle syndrome’. It has been reported in around 10% of menstrual cycles in normally fertile women. This is essentially when you have a normal LH surge, a functioning corpus luteum and get your period but no egg is released. 

Ten: the signal that you have ovulated: 

When an egg is released the mass remaining is the Corpus Luteum. This releases progesterone which causes the body temperature to rise 0.3-0.4 degrees for 3-4 days on average following. This is why some people like to measure core or Basal body temperature to really understand whether or not there are issues with ovulation.

However, the best way if you’re unsure if you’re ovulating or think you may be impacted by hormone issues is to get a blood test for progesterone with your doctor. 

Bottom line:

These test kits can be really useful if you have a totally normal cycle and no fertility issues. However, it is important to remember that they are not perfect and should not be totally relied upon. Once again, ideally the best route to conception is sex every 2-3 days of your cycle. If you think or know you have hormonal imbalances more precise readers like OvuSense (which captures the temperature rise as ovulation starts) is a great option. Click here for more. However, the first port of call should be your doctor who can take a blood test/do an ultrasound to make sure you are ovulating. 

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