The uterus is the cradle of life where the fetus is conceived and grows. So where does the fetus come from? The fetus is created by a man (his sperm) and a woman (her eggs). Where are eggs produced? Eggs are created in the ovaries. Ovaries are small walnut-like organs that are one of the main organs of a woman’s reproductive system.
The ovaries’ function is divided into two categories: the reproductive function to produce eggs and the endocrine function to produce and secrete the hormones estrogen, progesterone, and small amounts of testosterone. In fact, the two functions are closely linked to each other. What is the role of the ovaries? In addition to ovulation, they help to produce and secrete hormones to aid the uterus. When eggs are fertilized, the embryo is implanted into the wall. Eggs that have not ovulated are called follicles. The sizes of follicles are different. The smallest follicles can be seen under microscopes and the largest follicle can have a diameter of 2cm. Follicles are the structure where the eggs stay before their release.
Not only do women have a limited number of follicles, that number also decreasing as time passes. Follicles develop within a female fetus at about 5 months with about 1 to 2 million follicles, called primordial follicles. By the time the baby is born, the number of follicles is reduced by half. By puberty, it is reduced by another 50%. If a woman ovulates each month, 12 times a year, for a total of 30 years, that is more than 400 eggs ovulated. Eggs that are not ovulated or fertilized will die out. We know that taking birth control pill can help stop ovulation, but will this delay menopause? Possibly, but not necessarily since undeveloped follicles will die. Does this mean that if a woman menstruates then ovulation occurs? No. Sometimes, we will encounter anovulatory bleeding. Normally speaking, if a woman is healthy, she will ovulate once every month.
Patients tend to ask, what can I eat to help improve my ovarian function and delaying menopause? Because of today’s society and our focus on nutrition, it is unlikely that malnutrition will cause infertility. However over eating and anorexia are extreme cases that contradict this. The aging of the ovaries is determined by mainly genetic factors, not by what they eat. Some people say that massages can help but there is no proof that this will work. By age 35, your ovarian function will start to decrease. By age 40, your ovarian function will dramatically decrease. Women’s fertility is limited, so consider freezing your eggs while you are younger to maintain fertility longer.
Dr. Zhang,
While the follicles are certainly aging, do you think that lifestyle factors can effect follicular quality by impacting the environment of follicular recruitment? We often see improved egg quality, fertilization rates and increase numbers of follicules making it to blasts compared to previous cycles after significant lifestyle changes. How else can we account for this?
Hi Kirsten,
Lifestyle and environmental factors have been shown to affect reproduction and in particular ovarian function. For example, avoiding the inhalation of pollutants and avoiding unhealthy fried cooked food have been shown to protect ovarian follicles from environmental stresses and could potentially help produce better quality eggs… Additionally, taking vitamins such as vitamin D also proved to be beneficial for egg quality.