Cycle monitoring is a process of observing a woman throughout her menstrual cycle to observe a range of factors, such as how a follicle in the ovary develops during the cycle; to measure blood hormone levels throughout this process; and to determine whether and when ovulation is occurring.
Timing is Everything
Timing is very important when trying to get pregnant. Cycle monitoring is an important part of the initial fertility work-up, helping to determine if there are any issues with the process and timing of natural ovulation. It also plays a key role in the fertility treatment process, as it allows the doctor to time interventions appropriately in order to maximize chances of pregnancy.
Cycle monitoring of a natural cycle (otherwise known as a diagnostic cycle), inin which no fertility medications are used, is generally only required in the initial stages of fertility investigations. It helps the physician to gather information that can then be applied to fertility treatment cycles. Monitoring a natural cycle allows us to determine if there are any abnormalities in follicular development and the associated changes in hormones that normally occur in the absence of any fertility medications. This gives us information on what to expect in a medicated cycle, and to determine whether any additional medications or modifications in monitoring need to be considered (e.g. medication to prevent premature ovulation, monitoring early in a cycle when there is a history of early follicle development). Importantly, natural cycle monitoring has no higher pregnancy rate than timed intercourse in women that have regular cycles.
In a treatment cycle, the main role of cycle monitoring is to follow women while they are on fertility medications in order to time intercourse or intrauterine inseminations (IUI) appropriately. Fertility medications are either used for ovulation induction (OI) or controlled ovarian hyperstimulation (COH). In women who do not ovulate on their own, fertility medications are used for OI, to make a single follicle that grows and ovulates. In women who do ovulate regularly, fertility medications are used for COH, to make more than one follicle (usually 2-4 follicles) in order to increase chances of pregnancy above baseline.
Throughout the process of cycle monitoring, women are required to come in to the clinic for a series of blood tests and transvaginal ultrasounds. At the start of a cycle, the ultrasound is done to determine the antral follicle count. Follicles are little cysts that hold immature eggs. The number of follicles that are seen at the start of a cycle gives the doctor a sense of a woman’s ovarian reserve (the pool of eggs available in the ovaries at any point in time for potential pregnancy). This initial ultrasound also helps to ensure that there are no large cysts present which may prevent an appropriate response to the fertility medications. Bloodwork is also done at the start of a cycle to ensure that the baseline FSH (follicle-stimulating hormone) level is not elevated. An elevated FSH is a sign of decreased ovarian reserve and ovarian aging, and would decrease or eliminate the effectiveness of fertility medications. Throughout the cycle, the ultrasounds allow us to track growth of the follicles and thickening of the uterine lining. The bloodwork also helps monitor follicle growth, because as a follicle grows and its egg matures, the estrogen level in the blood rises. A sudden rise in LH (lutenizing hormone) level occurs just prior to ovulation and helps determine the right timing for intercourse or IUI.
Although cycle monitoring is very helpful to time intercourse or IUI while using fertility medications for OI or COH, it is important to realize that it has its limitations. Oral fertility medications (e.g. letrozole, clomiphene citrate) combined with IUI have a pregnancy rate of 8-10% per cycle, while injectable fertility medications (e.g. Gonal F, Puregon) used with IUI have a pregnancy rate of 15-18% per cycle. However, these numbers change significantly with various other factors. Advanced age of the woman, moderate or severe abnormalities with the sperm, and prolonged infertility despite treatment are important factors that decrease success with cycle monitoring. As a result, the general recommendation is that after undergoing three medicated cycles through cycle monitoring, patients should meet and discuss their next steps with their doctor. The purpose of this is to determine whether further medicated cycles are appropriate, or whether patients need to consider further treatment options to increase their chances of pregnancy (e.g. In Vitro Fertilization, or IVF). TRIO, as well as most fertility centres, has found that medicated monitoring cycles have limitations. If a pregnancy has not occurred by 3-4 medicated cycles, the patient will need other methods to conceive. Any further cycles will not work. Fertility treatment is always an individualized process, so we encourage you to speak with your doctor in order to determine which treatment is best for you and your partner, now and as time goes on.