claire_walker's profile

1 Message


122 Points

Saturday, May 23rd, 2015 9:53 AM

LH detection

I am thinking about buying the fertility monitor, but I am a little confused. It says to use with first urine of the day, but most material I've read (and the instructions on my OPK) say NOT to use morning urine as LH synthesises in urine later in the day.

83 Messages


890 Points

9 years ago

Thanks for contacting us with your question, Claire! 

Clearblue Fertility Monitor has been extensively tested in the laboratory and found to be 99% accurate at detecting the LH (Luteinising Hormone) surge in urine when a surge is present in the sample.  These accuracy studies were conducted using first morning urine samples. 

There are a wealth of studies concerned with identifying the time of day at which the LH surge is most likely to begin and the results show great variation.  However, it is widely accepted that the LH surge, once it has started, typically lasts for 1-2 days.  Therefore, providing an LH surge is present, most women using our test at the recommended 24 hour interval with their first morning urine sample  should therefore detect their LH surge meaning peak fertility is displayed.

For optimum product performance we recommend that you only use first morning urine when testing with the Clearblue Fertility Monitor.

We hope this information helps!