The cyclic menstrual cycle is predictable. In the first half of the cycle, care is taken to groom the best egg for fertilization. Once this egg reaches the maturity parameter; ovulation is triggered and the released oocyte sets out on its journey into the fallopian tube. Here it is fertilized by the sperm and then continues in the fallopian tube toward the uterus where the developing embryo implants. During the second half of the menstrual cycle, fertilization and embryo development is occurring in the fallopian tube. Importantly during this second phase, the lining of the uterus, the endometrium, is being cultivated for the embryo’s arrival. During this time, the endometrium is exposed to the pro-gestation-al hormone, progesterone.
Our ability to define precisely the phases of the menstrual cycle and to make reasonably accurate predictions toward optimal times for conception is based on the above knowledge. Tests previously offered through physician’s office and testing labs have transitioned to reasonably, reliable at-home tests. This transition driven in part by technology and by increasing costs of office-based services affords patients both simplicity and autonomy.
The ovulated egg has a very short existence as a sole entitity. Without fertilization, it disintegrates within 24 hours. Sperm, on the other hand, can live up to 4-5 days after ejaculation in the cervical canal. Thus, the limiting factor toward determining the fertile window is driven by knowning the time of ovulation. There are two major means available to determine the approximate time of ovulation: physiologic observation (cervical mucus and basal body charts), and measurement of physiologic metabolites (urinary LH [leuteninizing hormone], salivary screens).
There is an array of products available, each touted to be superior to the next. The at-home fertility testing market represents a billion dollar industry and is growing rapidly. Unfortunately, not all of these tests undergo the rigor of appropriate testing although many have been tested thoroughly. Nonetheless, the potential information that they may provide offers value to the patients and physicians alike.