Back to Basics: Fertility and the Menstrual Cycle

Back to Basics: Fertility and the Menstrual Cycle

How’s Your Menstrual Cycle?

At CNY Fertility, you will be asked a common question during your consultation:  How are your menstrual cycles? Have you ever wondered why this is so significant? Many women don’t give too much attention to their menstrual cycle, typically only concerning themselves with knowing that their period comes every month and when the best time is to conceive a pregnancy. For the many women who are having trouble conceiving, having some knowledge of what happens during their 28-day menstrual cycle may actually shed some light on your fertility treatment.

Your Cycle

The menstrual cycle begins on the first day of blood flow; this is counted as day 1. On average, a 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 eggs) to grow. This is the follicular phase. Typically, one follicle will become dominant and many others will degenerate. During fertility treatments, daily injections of  FSH and LH are added in order to produce 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 of a 28-day cycle, the pituitary secretes a large amount of LH, also known as 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 that fertilization can occur. Preparation of the uterus continues in anticipation of 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 released now becomes a corpus luteum cyst. The higher levels of LH signal the corpus luteum to produce progesterone. This progesterone is necessary for sustaining early pregnancy. Estrogen continues to be  produced as well. If pregnancy does not occur, production of LH and the FSH stops. Progesterone and the estrogen levels drop, and the uterine lining sheds as your monthly period. The cycle begins again.

Irregular Cycles?

There are many factors, including stress, diet, and exercise, which can affect this cycle and causing a hormonal imbalance. Also, conditions such as polycystic ovaries and ovarian cysts can affect normal menses due to elevated levels of estrogen.

At CNY Fertility, we want you to fully 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