WHAT MAKES YOUR OVARIES TICK
Insights about ovulation, fertility, PCOS and more.

An Interview with Jerilynn C. Prior, M.D. FRCPC

Dr. Jerilynn Prior is a professor of endocrinology at the University of British Columbia. Her major interests lie in women’s health and both doing and interpreting well designed, holistic studies. She is a pioneer in research involving women's menstrual cycles, ovulation, progesterone and bone loss.

JLML: It was from your groundbreaking research that I first learned that even young women often have menstrual cycles in which they menstruate but don't ovulate. As a result they don't make progesterone, and the stage is set in that cycle for estrogen dominance. What is the primary cause of anovulatory or non-ovulating cycles?

JCPrior: Ovulation disturbance, rather than being peculiar to a few women, is common in all of us at least intermittently. It is the body's dynamic way of responding to the stresses that we encounter in our lives.

I'll use myself as an example. I went on a very strenuous backpacking trip. There were personal clashes on the trip, and we didn't bring enough fuel to boil water so we didn‘t have enough food, and I lost weight. Due to this combination of strenuous exercise, personal conflict and weight loss, I had a short luteal phase, meaning I didn't make progesterone for 10 or more days. I knew that because I was taking my temperature (in my mouth, with a light digital thermometer) every morning before I got up.

JLML: How do you track your luteal phase with a basal temperature chart?

JCPrior: If you record your oral temperature every morning for an entire month using a digital thermometer, record the temperature in the evening before you go to bed, and record any illness or early or late rising, you can quantitatively determine which days of the cycle are high progesterone days. You can then take all of those daily temperatures from the beginning of one period until the day before the beginning of the next, and do an average of the temperatures. The point where your temperature goes above that average, and stays above it, is the beginning of the luteal phase. It will go back down when your period starts or just before. That's how easy it is to figure out your luteal phase length! That alone is valuable information for women who are having miscarriages that may be due to a short luteal phase.

JLML: I have found that women who are more aware of their cycles are often better able to self-treat for hormone imbalances.

JCPrior: The ovaries are so sensitive to emotional, physical, nutritional and over-exercise stresses that regular cycles, with normal ovulation, become a good indicator of hypothalamic well-being. However, at perimenopause when periods change, women shouldn't expect regular cycles. At that part of our life cycles, estrogen rises and progesterone decreases in an erratic fashion largely determined by decreasing ovarian inhibin production.

JLML: Can you tell our readers what inhibin is?

JCPrior: Inhibin is a tiny, funny (to us scientists anyway) little two-chain protein hormone that's made in the same part of the ovary that makes estrogen and progesterone. It plays a role in keeping the pituitary gland, which regulates hormones, in check.

My hypothesis, which is well supported from data, is that in the perimenopause inhibin drops before the ovaries run out of follicles. By taking the brake off of follicle stimulating hormone (FSH), ovarian follicles are over-stimulated and make high and erratic estrogen levels. Because of the chaos, ovulation rarely occurs and progesterone is either low or low for the amount of estrogen produced.

JLML: What else can you tell us about anovulatory cycles?

JCPrior: There are really two kinds of ovulation disturbance categories which I call “turned on” and “turned off.” The most common in younger women, say under forty, is the “turned off” ovary where the hypothalamic/pituitary axis simply isn't sending the signals to the ovary because of stress, becoming underweight, illness, or over-exercise, (often associated with all the others).

JLML: What is the biochemical mechanism behind that?

JCPrior: There's an integrating center in the brain that receives signals from its limbic system, temperature system, and sleep system for example, which tell this center that there's stress. Through a complicated feedback loop involving the hypothalamus, pituitary, ovary and adrenal glands, stress signals decrease the signals from the pituitary gland that tell the ovaries to ovulate.

Typically women with turned off ovaries are lean or slim, they tend to be colder than others, and often have small and sometimes under-developed breasts. They are hard striving kinds of people. The first stress-related change is shortened luteal [mid-cycle] phase, then non-ovulation. Only later does estrogen production get disturbed, and disturbances of cycle intervals such as a long cycle (normal cycles can be 35 days apart), develop. If the stresses and weight loss continue, amenorrhea can develop, which is no periods for six or more months.

The other kind of ovulation disturbance I called “turned on.” The woman experiencing this kind of ovulation disturbance will complain of weight gain, acne, and hair where she doesn’t want it. The biology of this is less clear, but it relates to insulin excess and insulin resistance, which have effects both on the brain by increasing LH [luteinizing hormone] levels, and directly on the ovary. Excess insulin sits on receptors on the theca cells, the outer coat of the ovary, and makes them more responsive to the hormonal environment, and therefore they make more androgens [male hormones].

JLML: Aha! So that's why a high sugar diet aggravates polycystic ovary syndrome. The excess sugar creates high insulin levels, which stimulate androgen production in the ovary, which suppresses ovulation.

JCPrior: The higher LH and the higher androgen levels set up a signal that inhibits the follicle from ovulating. Because each follicle grows and creates a lake of fluid around it, if it doesn’t burst and release its egg, a cyst is left. Therefore you get into a situation of high or normal estrogen levels, high androgens, and low progesterone. That condition is usually characterized by obesity, especially middle-of-the-body obesity, androgen signs such acne, oily skin, facial and breast hair, and head hair loss. Because estrogen tends to be higher with weight gain, these are the women who have a higher breast cancer and endometrial cancer risk. They may also have the worst PMS symptoms.

JLML: So this is yet another good reason to avoid sugar and refined carbohydrates such as white bread and pasta.

JCPrior: And it's another good reason to get plenty of aerobic or endurance-type exercise, which is one of the best ways of getting the insulin levels down and decreasing PMS.

With turned on ovulation disturbances you need to correct three problems: The first is to bring progesterone into balance –and for this you use physiologic doses of progesterone. Next, you often you need to block the effect of the male hormone. There's a medicine called spironolactone which I use that blocks androgen action at the cell level. Finally, if a person has a family history of diabetes or is quite obese, then I may use a drug called metformin that sensitizes the body to insulin and allows the insulin levels to go down.

JLML: I have found that supplemental progesterone, a good amount of exercise, and a low sugar, low simple carbohydrate andlow fat diet with plenty of vegetables will often restore balance.

JCPrior: That can work for women who haven't become too obese and who are motivated to stick to the diet and exercise so they lose the weight.

JLML: What are some other body signals that a woman could notice to tell whether she has ovulated in a given month?

JCPrior: Besides basal body temperature, the sign that's most indicative that ovulation has occurred is premenstrual high lateral breast tenderness, at the sides of the breasts under the armpits. If the breasts are very sore up front and over the nipples, that's a sign of high estrogen. Soreness on the sides and in the front doesn't help determine whether ovulation has taken place.

This interview was originally published in the John R. Lee, M.D. Medical Letter. Although the newsletter is no longer published, you can find many articles from it on this website.