Fertility blood test: Why does it need to be cycle days 2-5? - Levy Health (2024)

Knowledge

Understanding your menstrual cycle is essential for various reasons, particularly if you’re undergoing fertility treatments or monitoring your reproductive health. Knowing which days correspond to Day 2 through Day 5 of your cycle can be especially useful for timing treatments, grasping your fertility window, and making informed decisions about your reproductive health. Here’s a clear guide to help you determine Day 2 through Day 5 of your cycle.

When you test your fertility with LEVY Health, your basic reproductive hormone levels (including FSH, LH, TSH, Prolactin, Estradiol, Progesterone, Anti Mullerian Hormone, Testosterone, DHEAS, SHBG, and Free Androgen Index) will always be checked, regardless of whether you have regular or irregular cycles. We also make custom recommendations for other biomarkers to be tested based on your personal health background. It’s crucial to have your blood tested between the 2nd and 5th days of your cycle…and here’s why.

Certain reproductive hormones (FSH, LH, E2, and progesterone) fluctuate quite a bit during the course of the menstrual cycle. In order to get an accurate reading of these hormones, you need to measure them all at the beginning of the cycle (days 2-5), because this is when they are the most stable.

At the beginning of the cycle, FSH, LH, and E2 are low. FSH, or follicle-stimulating hormone, is responsible for growing and maturing the follicles in your ovaries that hold eggs. FSH levels rise to promote growth of the follicles and to prompt the secretion of estradiol (E2), which also plays an important role in ovulation. As you approach the middle of the cycle, LH surges, triggering release of the mature egg in ovulation. Following ovulation, the ovaries produce more progesterone to prepare the uterine lining for implantation.

Therefore, it’s crucial to test these hormones when they are at their baseline level (before they start to rise) to get a correct result. If you were to measure these hormones at a different time, say in the middle or towards the end of the cycle, you would get a completely different reading, and it wouldn’t be meaningful for your fertility. In order to get a full picture of your reproductive health, it’s necessary to look at your levels of these hormones along with other important biomarkers.

So while it may be a bit frustrating to have to wait until the beginning of your next cycle to get your blood drawn, we assure you it’s definitely worth the wait!

How do you know when it’s cycle days 2-5?

In menstrual cycle terms, Day 1 is the first day of full menstrual bleeding (not just spotting). Thus, Days 2 through 5 are the days following the start of your period. These days typically fall within the early follicular phase of your cycle, a period when your body begins to prepare for ovulation.

Step-by-Step Guide to Determining Days 2-5

1. Track the First Day of Your Period:
   • Identify Day 1: The first full day of menstrual bleeding is considered Day 1. This is the first day you experience a regular flow of blood.
   • Record Your Period: Use a calendar, a period tracking app, or a journal to note when your period begins. Consistent tracking helps you pinpoint your cycle days accurately.
2. Count the Days from the Start of Your Period:
   • Day 2: The day following the first day of your period.
   • Day 3: Two days after the first day of your period.
   • Day 4: Three days after the first day of your period.
   • Day 5: Four days after the first day of your period.
3. Consider Your Cycle Length:
   • Regular Cycles: If your cycle is regular, tracking these days should be straightforward.
   • Irregular Cycles: If your cycle is irregular, you might need to track your periods over several months to establish a pattern and accurately determine these days.

Even if your cycle is very irregular and the length varies quite a bit month to month, it’s still important to test at the beginning (between the 2nd to 5th day) to get a proper reading of your hormones.

The only exception here is if you have amenorrhea, or no period at all. Women with amenorrhea can usually get their blood drawn at any time, but sometimes may need to get an ultrasound first. In case the uterine lining is very thick, a doctor may need to induce menstrual bleeding before testing reproductive biomarkers. If you don’t have a period, check with the LEVY Care Team or ask your OB-GYN prior to having your blood drawn.

Why Knowing Days 2-5 is Important

1. Fertility Treatments: Many fertility treatments and tests are scheduled based on specific cycle days. For instance, certain diagnostic tests or hormone checks are best performed during the early follicular phase.
2. Ovulation Tracking: Understanding these days helps in predicting ovulation and optimizing the timing for conception attempts or fertility treatments.
3. Health Monitoring: Regular cycle tracking can reveal patterns, irregularities, or changes in menstrual health, which are important for overall well-being and planning.

Accurately determining Days 2 through 5 of your cycle allows you to make more informed decisions about your fertility and overall health. Consistent tracking and awareness of your cycle are key to effective reproductive health management.

• Ovarian Reserve. ReproductiveFacts.org from the American Society for Reproductive Medicine. Accessed 24 August 2022.
• Fertility blood tests: Information for patients. Sheffield Teaching Hospital, NHS Foundation Trust.
• FSH, E2 & Progesterone. Fertility Associates. Accessed 24 August 2022.
• Day 3 FSH Fertility Testing of Ovarian Reserve – Follicle Stimulating Hormone Test. Advanced Fertility Center of Chicago. Accessed 24 August 2022.
• Hehenkamp WJK et al.: Anti-Müllerian Hormone Levels in the Spontaneous Menstrual Cycle Do Not Show Substantial Fluctuation. The Journal of Clinical Endocrinology & Metabolism, 2006;91(10):4057-4063.