Path To Fertility Blogger Lisa Rosenthal  

Lisa Rosenthal has over twenty-five years of experience in the fertility field, including her current roles as Coordinator of Professional and Patient Communications for RMACT and teacher and founder of Fertile Yoga, a class designed to support, comfort and enhance men and women's sense of self. Her experience also includes working with RESOLVE: The National Infertility Association and The American Fertility Association, where she was Educational Coordinator, Conference Director and Assistant Executive Director

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Fertility Testing on Day 21


Wednesday text
Good morning. Today is Wednesday, our day to focus on the medical aspects of fertility and treatment. Fertility treatment often has a language all it's own. Here's another term that is significant in testing and treatment that you may not understand as thoroughly as you might like, Day 21.


On Day 21 of your cycle, your fertility specialist will want to check the levels of progesterone and estradiol (E2) in your system and the thickness of your endometrium (uterine lining).


Day 21 testing checks a woman’s progesterone level to confirm that ovulation has occurred. It is done on the 21st day of the menstrual cycle (Day 1 is the first day of flow, not including any spotting). A low Day 21 progesterone level suggests the cycle was anovulatory (no egg was produced). If no egg is produced, pregnancy cannot be achieved.


The timing of ovulation, and the associated peak in progesterone, is related to the subsequent menstrual period, not the preceding one. In an average cycle of 28 days, the time between ovulation and the next period is about two weeks, so progesterone is measured about seven days before the expected period, or on Day 21. However, if a woman’s cycle is longer or shorter than 28 days, the testing day will be adjusted accordingly. For example, a woman with a 35-day cycle would be tested for progesterone on Day 28.


Serial estradiol (E2) levels are often measured for monitoring superovulation in intrauterine insemination (IUI) and in vitro fertilization (IVF) treatment cycles.


If you are not ovulating, there are steps that can be taken to help release the eggs, including drugs. Your fertility specialist will discuss these options with you.


An ultrasound exam is also used to measure your uterine lining to determine if it is thick enough for a fertilized egg to implant.


Day 21, explained. If there are other phrases that you hear and would like to understand, try our glossary. Our doctors at RMACT, along with our excellent nursing staff, have written it, for you.

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