Which day of my cycle should I test?

Your answers to the Online Health Assessment determine which hormones to test and on what day of your cycle. But whichever day you test, it’s always best to test in the morning, within 3-4 hours of waking up after fasting for at least 8 hours. Some hormones also fluctuate throughout the day - so collecting your sample first thing gives the most accurate readings.

We usually recommend testing on the third day of your period. This is because whilst  hormones such as Anti-Müllerian Hormone (AMH), Thyroid-stimulating hormone (TSH) and Prolactin can be tested any day, some hormones such as Follicle-stimulating hormone (FSH), Luteinising hormone (LH), and Oestradiol (E2) fluctuate throughout your cycle. 

Since different hormones fluctuate throughout your cycle, if you are not on hormonal contraception and your cycles are regular, you must collect your sample on day 3 of your menstrual cycle. This is when your fluctuating hormones are at a baseline and therefore we get the most accurate results. But, if you use hormonal contraception you can test on any day. This is because we don’t test your cycling hormones (LH, E2, FSH) that need to be tested on day 3 of your cycle as these hormones are affected by your contraception. 

Please note: If you are on hormonal contraception, we will not be able to test your menstrual cycle hormones (FSH, LH and E2).  Additionally, there is some evidence that AMH levels may be moderately temporarily lowered whilst using hormonal contraception. . If you’d like to test your menstrual cycle hormones, you will need to come off of your hormonal contraception for at least 3 cycles. Please see FAQ about testing on hormonal contraception.

If you have short periods, please test on Day 3 of your cycle. You don’t need to be bleeding as testing does not depend on flow. If your cycles are shorter than 21 days, please test on Day 2 of your cycle instead. 

If you have irregular periods we generally advise you to test on your next day 3, rest assured you can wait, you just need to use before the expiry date stated on the back of the kit. However, if your cycle is longer than 45 days, we advise you to test on any day, as it can be difficult to identify what’s causing your irregularities and means you can get the information you deserve, sooner.