Is ovary size important?

As is the case with all the organs in our bodies, over our lifetime, ovaries go through changes that affect not only their size but also how they perform. The ovaries are situated between the uterus and the fallopian tubes. They are essential to reproduction and, therefore, to the survival of the human race.

The ovaries begin to develop when female embryos are around 8 weeks old and during pregnancy they undergo a number of changes that prepare them for their role in reproduction when a woman is in her childbearing years.

How ovaries evolve in size and other characteristics: From birth to menopause

• A newborn girl will normally have two ovaries, each one measuring 1 cm in diameter and weighing between 250 and 350 mg. They contain all the cells that will be ovulated later on in life during successive menstrual cycles (400 to 500 ovulations between the ages of 35 and 40 years). This means that the egg that matures, ovulates and travels to the fallopian tubes each month is the same age as the woman herself. New eggs are not generated.
• During puberty, and as a result of complex hormonal changes, ovulation takes place for the very first time. The ovaries will have increased progressively in size during infancy and their weight will have increased tenfold. During adulthood, ovaries reach an average size of 3.5 x 2 x 1 cm, equivalent to a volume of between 3 and 6 ml.
• Over time, the eggs in the ovaries decrease and ovulations eventually cease. At this point, the woman begins what is known as the menopause. During and following this phase, the ovaries decrease in size until they become similar to when the woman was first conceived.

How big is a normal ovary in millimeters?  Can its size change?

• During adulthood, through a 3d ultrasound scan (long, wide and depth) ovaries reach an average size of 40 x 30 x 20 mm, equivalent to a volume of between 4 and 6 ml.
• Physiological shape may change in every ovarian cycle due to the dominant follicle growth. This follicle may reach about 22 or 24 mm in the middle of a menstrual cycle, then breaks, causing ovulation.

Is there a link between ovary size and how easy or difficult it is to get pregnant? 

We know that ovary size is linked to the number of potential eggs that will be available during a woman’s fertile period. A young woman with small ovaries has a greater chance of having difficulties achieving a normal full-term pregnancy. This is because she will have a lower egg reserve.

Does having large ovaries always mean an increased ability to reproduce?

Having large ovaries does not mean that a woman is more fertile. For example, ovaries can be large in size as a result of cysts or tumours. They are more commonly large in size in women with so-called polycystic ovaries. In such cases, it is frequently linked to an abnormality in ovulation and, therefore, to varying degrees of difficulties getting pregnant.

Diagnose the size of the ovaries

As mentioned above, size and performance are important and there are simple and accessible tests in order to be able to assess both parameters.

• Ultrasound scans can be used to take quick and easy measurements. They indicate not only ovary size but also something that is, perhaps, even more important: they enable us to count the number of follicles (structures that are visible in ultrasound scan images, the quantity of which is linked to ovarian reserve).
• We can use a simple blood test to determine the levels of hormones linked to ovarian function, including anti-Müllerian hormone, a reliable indicator of the egg reserve in a given ovary.

Menopause ad the ovaries size:

Having big or small ovaries affects the menopause arrival?

One of the ovarian reserve indicator is the number of follicles a woman shows in her fertile age.

The total number of follicles in an ovary is related with its size. The bigger the number of follicles, the larger the size and vice versa. This way, the ovarian size is related with a woman’s “reproductive life expectancy” and the appearance of menopause.

If a young adult woman has a lower ovarian size to what is considered as normal and has a low count of follicles, has a high probability of having an earlier menopause than a woman with normal or bigger ovarian size.

How menopause affects the size of the ovary:

With age, and in a physiological way, the number of ovarian follicles decreases, the hormone production falls, ovulation stops and the ovarian size is reduced to an average size of 20 x 7,5 x 10 mm. The equivalent in volume would be lower than 2 ml.

What is the ovarian atrophy?

The term atrophy means the lack of development or decrease in size of organ or tissue.

In the first case and applied to the ovary, the total or partial lack of development will mean the absence of menstrual cycles or its early cease (before 40 years of age). See more about Premature Ovarian Failure (POF).

In the second case, the passing of time entails and ageing which is shown by a ovarian size progressive reduction, accompanied by the whole peri-menopause clinical entourage until the complete menstruation cease.

At Instituto Bernabeu, we have set up a pro-fertility planning unit (Fertyplan) where we evaluate and provide a personalised assessment of a patient’s potential risk of reproductive issues. This enables patients to take decisions on how and when to plan for future pregnancies.

IT MAY ALSO BE OF INTEREST TO YOU:

• What is ovarian reserve? What role does it play in fertility?
• Premature Ovarian Failure, Can I be a mother? Causes, symptoms, diagnosis, treatment and prevention
• Polycystic Ovary Syndrome
• Genetics in premature ovarian failure and menopause
• Ovarian Hyperstimulation Syndrome

Dr Lydia Luque, gynaecologist at Instituto Bernabeu.