Back to Basics: Fertility and the Menstrual Cycle


At CNY Fertility Center, founded by Dr. Robert Kiltz, with offices in Latham, Syracuse and Rochester, you will be asked a common question at your consultation. How are your menstrual cycles? Have you ever wondered why this is so significant?
Many women do not give to much attention to their menstrual cycle. Typically only concerning themselves with knowing that their period comes every month and when the best time to conceive a pregnancy is. For the many women that are having trouble conceiving, having some knowledge of what happens during this 28 day menstrual cycle may actually shed some light on your fertility treatment.
The menstrual cycle begins on the first day of blood flow; this is counted as day 1.On average the menstrual cycle can range from 24-35 days. The menstrual phase may last 4-8 days. On day 1 the hypothalamus is telling the pituitary gland to produce FSH, follicle stimulating hormone, and LH, luteinizing hormone. The pituitary is also telling the ovaries to produce estrogen. The production of FSH tells the follicles (tiny cysts which house the egg) to grow. This is the follicular phase. Typically one follicle will become dominant and many others will degenerate. During fertility treatments FSH and LH are added through daily injections resulting in more follicles. The dominant follicle(s) is producing estrogen and a small amount of progesterone. The estrogen is causing the uterine lining to thicken in preparation for an embryo to implant. Once the follicle(s) reach about 20mm in size, on average around day 14 if the cycle is 28 days, the pituitary secretes a large amount of LH, the LH surge. There will also be a surge in FSH, these two combined signal the ovary to rupture the follicle(s), and this is ovulation. It is at this time fertilization can occur. Preparation of the uterus continues for fertilization. This is now considered the luteal phase of the cycle.  The ONLY true test that ovulation has occurred is when a pregnancy is established.
The pituitary continues to produce LH and the hypothalamus will produce gonadatrophin releasing hormone (GnRH). The follicle from which the egg was releasing now becomes a corpus luteum cyst. The higher levels of LH signal the corpus luteum to produce progesterone. This progesterone is necessary in sustaining early pregnancy. There continues to be estrogen produced also. If pregnancy does not occur the LH and the FSH stop. The progesterone and the estrogen drop and the uterine lining sheds. The cycle begins again.
There are many factors which can affect this cycle, causing a hormonal imbalance, such as stress, diet and exercise. Also conditions such as polycystic ovaries and ovarian cysts can affect normal menses due to elevated levels of estrogen.
At CNY Fertility Center we want you to understand your treatment. We are here to help you achieve your goal of conceiving a baby. We will ask you about your menstrual cycle in order to gain valuable information which will help plan your treatment. If you do not fully understand any aspect of your treatment, please do not hesitate to ask one of our providers.
Sheila Miller, RT RDMS
Ultrasonographer and Radiology Technician
CNY Fertility Center, Latham, NY