At Modern Fertility, we know there’s no such thing as a “one size fits all” approach when it comes to reproductive health. Periods are unique, and that’s ok! If your Modern Fertility kit requires testing on Day 3 of your period, here are some helpful tips for getting started. 

Why do I need to collect my blood sample at a certain time in my cycle?

Great question! Many of the hormones we test for fluctuate throughout the menstrual cycle. Doctors consider Day 3 of your period the baseline level for these hormones. When you test on this day, we can interpret your results and what they mean in the correct context. You can read more about the science behind Day 3 testing on our blog.

How do I pinpoint Day 3?

Count Day 1 of your period as the first day of full flow. For instance, if you have spotting on Monday and Tuesday, and then your full flow begins on Wednesday before 5 pm, Wednesday would be "Day 1" and you would test on Friday - "Day 3." 

What counts as full flow?

It’s not uncommon to experience spotting before your period really gets going — you know you’re at “full flow” if your period is heavy enough to need a tampon/ pad/ menstrual cup etc.  

What if my period only lasts 1 or 2 days?

If you only have one or two days of full flow, go ahead and test on "Day 2," or the day after your full flow began. So, if you have 1-2 days of spotting and then 1 day of full flow, test the day after that. You can still count "Day 1" as the first day of full flow.

What if my period is irregular, or doesn’t come very often?

Modern Fertility Hormone Tests are good for two years, so you’re welcome to hold onto your kit until your period arrives! 

What if I’m not on birth control, but I don’t get a period at all?

There are lots of reasons someone might not get a regular period! Send us a note at and our team will get right back to you with next steps.

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