You can take the Modern Fertility Hormone Test while breastfeeding, but it's good to note that breastfeeding can impact some of the hormones in the panel. (Prolactin, for example, plays a big role in lactation!) If you've recently given birth, we recommend waiting to test until your period returns.
If you test while still breastfeeding (after your period has returned) your levels may be different than other people in your age group. In this case, we recommend using your results as a conversation starter with your doctor. You can bring your raw results to your appointment, and you and your doctor can work out a plan that works for your body and your fertility goals.