When people begin thinking about future fertility—whether they’re planning for pregnancy in the next few months or the next few years—the same questions come up repeatedly: What labs should I get? Does my birth control affect the results? What should I be doing now to prepare? Fertility preparation doesn’t need to be overwhelming. It’s really about understanding your cycle, supporting the foundations of health, and knowing which hormone tests are meaningful—and which aren’t—depending on where you are in your reproductive journey.
Can You Test Hormones While on a Hormonal IUD?
A hormonal IUD such as Mirena or Kyleena releases levonorgestrel locally into the uterus. Most people still ovulate, but their cycles can become irregular, lighter, or unpredictable. Because of this, most hormone-based fertility tests lose accuracy.
Day-3 testing (FSH, LH, estradiol) is only reliable when someone has predictable cycles with a true menstrual bleed. These labs are meant to reflect early-follicular-phase ovarian signaling. If someone’s “Day 1” is inconsistent or affected by IUD-related spotting, it becomes unclear whether the bloodwork reflects a real early-cycle state—making interpretation difficult and often misleading.
This is why the majority of hormone testing—FSH, LH, estradiol, progesterone, ovulation confirmation—is not considered reliable while on a hormonal IUD.
However, there are tests that remain accurate because they are not dependent on ovulation timing or cycle regularity.
Labs that are reliable while on a hormonal IUD:
-
Thyroid panel
-
Iron + ferritin
-
Vitamin D
-
B12 / folate
-
Blood sugar markers (fasting glucose or insulin if needed)
These foundational health markers matter deeply for fertility and early pregnancy, and can be checked anytime—whether or not you have natural cycles.
What Hormone Tests Should You Do Once Off a Hormonal Contraception?
Once you have natural cycles and predictable menstruation again, we can begin meaningful hormone evaluation. The most helpful tests include:
Day 2–3 Labs (with normal cycles):
-
FSH
-
LH
-
Estradiol
These tests show how your ovaries are working, how well you’re making eggs that month, what your estrogen is doing early in your cycle, and how well your brain and ovaries are talking to each other.
Ovulation Confirmation
Progesterone at Peak Cervical Mucus Day + 7
-
-
This confirms ovulation quality and mid-luteal hormone sufficiency.
-
It is not accurate to just test on “Day 21”—it must be 7 days after ovulation, which varies cycle to cycle and person to person.
- As you can see in the image below the progesterone peak is quite narrow, if you ovulated on day 16 and tested on day 21 you would measuring the progesterone value much lower then it actually was at it’s peak.
-
Progesterone is essential for maintaining a fertilized egg (aka pregnancy). It is often affected by stress. Together, these labs give a clear, evidence-based picture of your reproductive hormones at the correct cycle moments.
from: https://lesleyoconnornaturopath.com.au
Where Does Cycle Tracking Fit In?
Cycle tracking helps identify ovulation, fertile days, and menstrual patterns with far more accuracy than apps or predictions. It also helps you time your progesterone test correctly. (I will link our full Cycle Tracking course soon!)
The Heart of Preconception Care: Foundations, Not Just Labs
Even with all the hormone testing options available, the truth is that your foundational health plays the biggest role in preparing your body for pregnancy. That includes your:
-
Iron and ferritin status
-
Vitamin D levels
-
Thyroid health
-
Stress regulation
-
Nutrient intake
Fertility work isn’t just about trying to conceive—it’s about ensuring you have the energy, nourishment, and emotional capacity to take care of yourself and eventually a whole other human being. A helpful mindset is asking yourself: How can I support my body so fully that I’m overflowing? That overflow becomes the reserve that supports conception, pregnancy, and postpartum recovery.
Final Thoughts
Whether your goal is to conceive in six months or three years, the most important steps right now involve stress support, nutritional foundations, and understanding your own cycle patterns. Hormone testing has its place—but timing and context matter greatly.
For a deeper dive into nutrition, lifestyle, and preconception planning, you can explore my short prenatal support guide here.