Ovarian function

Ovulation

Ovulation is when the ovary releases a fully developed egg. Each egg matures within a small fluid-filled sac called a follicle. During each menstrual cycle, one follicle is selected to develop further under the influence of follicle-stimulating hormone (FSH).

As the follicle grows, it produces oestrogen, which helps build up the lining of the uterus, known as the endometrium, in preparation for a possible pregnancy. Once the egg has matured, a surge in luteinizing hormone (LH) triggers its release from the ovary. The egg then enters the fallopian tube.

For fertilisation to occur, healthy sperm must travel through the reproductive tract and reach the egg. If a sperm successfully penetrates the egg, fertilisation takes place, forming an embryo.

After ovulation, the ovary produces progesterone, a hormone that supports the uterine lining and makes it more suitable for implantation. If fertilisation does not occur, hormone levels fall and the uterine lining is shed as a menstrual period. If fertilisation does occur, the embryo may implant into the lining of the uterus, marking the start of pregnancy.

Ovarian Function
There are several ways to determine whether ovulation is occurring. These may include ultrasound scans, urine testing, or blood tests. If ovulation is not happening at the expected time—or not occurring at all—there are treatment options that can assist. Your doctor will guide you through the most appropriate approach based on your individual situation.

Ovarian Reserve
Ovarian reserve refers to an estimate of the number of eggs remaining in the ovaries. While certain tests can provide an indication, they cannot determine the exact number of eggs or assess their quality. At present, there is no reliable test to directly measure egg quality.

An ultrasound can be used to count the number of small resting follicles in the ovaries (often called the antral follicle count), which offers a general idea of egg supply. A blood test measuring Anti-Müllerian Hormone (AMH), produced by these follicles, can also help estimate ovarian reserve. What is considered a “normal” AMH level varies with age. Together, the ultrasound findings and AMH level help classify ovarian reserve as low, normal, or high. Although individual responses to fertility treatments can differ, these results can help predict how the ovaries may respond to stimulation medications.

Hormone Testing
Blood tests are also used to assess reproductive hormones involved in ovarian function, including follicle-stimulating hormone (FSH) and progesterone. The timing of these tests is important. FSH is typically measured early in the menstrual cycle, around day 2 or 3, while progesterone is usually checked about a week after ovulation. Your doctor will advise you on which tests are appropriate and when they should be performed.