A bit of fat is good!
Women’s reproduction has fluctuating hormones which release an egg every month at ovulation and build up the womb or uterus lining, which is shed if there is no pregnancy. There is a small amount of male sex hormones or androgens produced by the adrenals in women. Normally an enzyme in the fat cells of women eliminates these androgens by converting them to oestrogens. So some fat is good! That’s why when women starve voluntarily, as in anorexia nervosa, androgens build up and impair the menstrual cycle. Often these women stop ovulating or have irregular cycles.
Extreme physical activity and psychological stress
This loss of body fat applies to extremely physically active women too. Also for female athletes the interaction of endorphins and enkephalins, prolactin* and glucocorticoids* (‘steroids’) affect the ovaries by making them less sensitive to hormones that promote ovulation (luteinizing and follicle stimulating hormones). Cycles again become irregular and longer. Psychological stress disrupts sex hormones in the same way too. For both types of stress, glucocorticoids (and prolactin) released during stress also cause inhibition of progesterone which is necessary to help the fertilised egg implant and a pregnancy continue. Oestrogen is decreased too, besides impacting on egg development it leads to reduced sexual desire. Also oestrogen is thought to protect against cardiovascular disease and osteoporosis.
An increasing frequent stressor seen in my practice is women in highly demanding jobs working long hours and this is thought to increase the risk of miscarriage (especially when the woman has little control over her work). The delivery of blood to the foetus is very sensitive to the blood flow in the mother and uterine blood flow can be disrupted by stress. Foetal heart rate has been shown to closely track the mother, so an increase in heart rate in the mother can be seen a minute or so later in the foetus. Studies have shown that increased adrenaline decreases blood flow to the uterus – dramatically in some cases. Severe stress besides increasing the likelihood of miscarriage also increases the risk of preterm birth, an effect thought to be due to elevated glucocorticoids.
Assisted Conception – IVF
When a couple struggle with getting pregnant this brings massive, often overwhelming psychological stress – the strain on the relationship, disruption of daily activities, charting her most fertile time, having sex on demand, the two week wait to see if it’s worked this time, the estrangement from friends and family, hearing yet another friend has become pregnant and the rates of depression. Then they may enter the even more stressful world of in vitro fertilisation (IVF), where women are subject to painful daily injections of synthetic hormones and hormone suppressors that can have unpleasant side effects such as hot flushes, headaches, bloating and mood changes or worse, be life threatening in the case of overstimulation of the ovaries. The stress piles on – regular visits to the clinic for scans, should I tell work, how can I get time off, is the news good or bad today, are there enough follicles, are they the right size, is the womb lining thick enough, have the eggs fertilised, one or two embryos to transfer? Then after the embryo is put back, there is the wait to see whether you have to try the whole thing again.
There aren’t enough good quality studies yet to say decisively whether women who are more stressed going through IVF are more likely to be unsuccessful, though the studies are saying a strong maybe. IVF clinics welcome women having acupuncture during the IVF process, as they know it helps reduce stress.
If you want a more detailed biological explanation of the mechanism of stress on the body and related disease (it’s both fascinating and scary!) and where much of this information in this article has been sourced, I’d recommend reading Robert Sapolsky’s Why Zebra’s Don’t Get Ulcers.
*Glucocorticoid: A hormone that predominantly affects the metabolism of carbohydrates and, to a lesser extent, fats and proteins (and has other effects). Glucocorticoids are made in the adrenal gland and chemically classed as steroids. Cortisol is the major natural glucocorticoid.
*Prolactin interferes with the activity of progesterone. In sufficient quantities it also works to stop ovulation. It plays a major role during stress and exercise, and is the main reason that breast-feeding is such an effective form of contraception (breast feeding causes prolactin secretion).