The Monthly Ovulation Cycle

Do you have irregular periods? Is your cycle extremely long or very short? Ovulation problems like these are among the most common causes of infertility. Once you identify any issues with your cycle, your physician can then help you address them— an important step in your family planning process.

The Cycle: Step-by-Step

The rise and fall of levels of hormones during the month is what controls the menstrual cycle. Cycles can range anywhere from 21 to 35 or more days in adult women.

Day 1: Your menstrual cycle starts on the first day of bleeding.

• The lining of the uterus is shed for approximately five days. At the same time, several follicles (fluid-filled sacs inside the ovaries that contain eggs) begin to mature and develop.
• The hormone FSH (which stands for Follicle Stimulating Hormone) develops the eggs.
• Estrogen levels rise and cause the lining of the uterus to start building up again.

Day 14*: About two weeks into the monthly cycle, your levels of the hormone LH (Luteinizing Hormone) rise sharply.

• Within 24 to 48 hours, the most mature follicle in the ovaries bursts and an egg is released. Some women experience a little twinge of pain in one of the ovaries around this time.
• Following the LH surge and ovulation, the progesterone level rises to prepare the lining of the uterus for the embryo.

Day 15*: The egg travels from the ovary into the fallopian tube.

• As the egg nestles in the end of the tube, it may come in contact with sperm. If the sperm penetrates the egg, fertilization occurs.

Day 20*: The fertilized egg continues its journey to the uterus, where it may or may not successfully implant in the lining of the uterine wall. If the egg was not fertilized, it simply absorbs.

• As the embryo implants, it begins to produce the hormone hCG (Human Chorionic Gonadotropin), which helps maintain the lining of the uterus during the implantation process.
• By day 28, the hCG levels are high enough that a urine pregnancy test would come back positive.

Keeping the Balance

Keep in mind that the cycle is controlled by your hormones, and each hormone fluctuation dovetails into the next. That’s why in order for conception to occur, it’s critical that each hormone performs as expected; if anything is out of balance, the entire process is affected.

Fortunately, once any ovulation problems are identified, there are a variety of steps your physician can take to correct them.

*Exact cycle days can vary, as some women’s cycles are as short as 21 days, while others can be 35 days or longer. The average for most women is between 27-28 days.