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Obesity and infertility

Posted Nov 18 2008 12:17am

Obesity is one of the prices some of us pay for modern society’s prosperity . Not only is food easily available ; it’s also inexpensive; and because of modern conveniences, there is little need to walk or be physically active.
Being overweight affects everything. You can take lists of diseases from every specialty and find some obesity-related ones in each. Hypertension, coronary artery disease, pulmonary problems, diabetes, skin health...the lists are endless. One of them is being infertile.
How does obesity interfere with fertility? What is the connection between obesity and PCOD ? obesity and hypothyroidism ? obesity and insulin resistance? How do you judge whether you are obese or not ? And how does one lose weight ? Lots of complex questions – and no easy answers ! Let’s look at them one by one.
While most women are happy to blame their obesity on hormonal problems ( what used to be called “ glandular deficiency “ in unkinder times ) , usually the underlying reason for obesity is simple – the caloric intake is more than caloric expenditure. However, sometimes hypothyroidism can cause both obesity and infertility, so you should start by doing a simple blood test for TSH levels to check for this. Thyroid problems are easy to diagnose and usually easy to fix. However, what if you are amongst the vast majority of overweight women who are infertile, and have normal thyroid function ?
We first need to understand how obesity causes biochemistry to gang up on normal ovulation . There are three sources of estrogen in the body: the ovary (directly) ; as well as the adrenal glands; and fat cells (indirectly). The ovary makes estrogen in quantities which depend upon the phase of the menstrual cycle. The adrenal glands make androgens (male hormones such as androstenedione. Since all of these sex-hormones ( including testosterone and progesterone) are derived from cholesterol, these hormones are converted back and forth in the cells . In the case of the adrenal androstenedione, fat cells can convert it into an estrogen called estrone. If you're significantly overweight, a steady oversupply of estrogen ( from the “peripheral” conversion of androstenedione to estrogen in the fat cells ) will blunt the peaks and valleys of the ovary's function, which ultimately interferes with ovulation and can cause infertility.
Many obese women also have polycystic ovarian disease
( PCOD) . Patients suffering from PCOD have multiple small cysts in their ovaries ( the word poly means many). These cysts occur when the regular changes of a normal menstrual cycle are disrupted. The ovary is enlarged; and produces excessive amounts of androgen and estrogenic hormones. These prevent ovulation, which causes infertility. This diagnosis can be confirmed by vaginal ultrasound, which shows that both the ovaries are enlarged; the bright central stroma is increased ; and there are multiple small cysts in the ovaries. These cysts are usually arranged in the form of a necklace along the periphery of the ovary. Blood tests are also very useful for making the diagnosis. Typically, blood levels of hormones reveal a high LH ( luteinising hormone) level; and a normal FSH ( follicle stimulating hormone) level ( this is called a reversal of the LH : FSH ratio, which is normally 1:1); and elevated levels of androgens ( a high dehydroepiandrosterone sulphate ( DHEA-S) level, which is called hyperandrogenemia.
And that’s not all ! To make a bad situation worse, obesity aggravates insulin resistance. Insulin is a hormone secreted by the pancreas which helps the body’s cells to utilize blood glucose (sugar) by binding with receptors on cells ( like a key would fit into a lock), so that the glucose can pass from the blood into the cell, where it is used either to supply energy. In insulin resistance, the body's cells have a diminished ability to respond to the action of the insulin hormone. In order to compensate for this, the pancreas needs to secrete additional insulin. This results in high levels of insulin in the blood ( hyperinsulinemia); and a diagnosis of hyperinsulinemia can be made if fasting insulin levels are over 15 uU/ml. In about one third of people with insulin resistance, when the body cells resist even these high levels of insulin, the glucose builds up in the blood , resulting in type 2 diabetes. High levels of insulin also cause hyperstimulation of ovarian steroid production , thus worsening the vicious cycle because of increased production of estrogens and androgens.
Obesity has also been associated with an increased risk of early pregnancy loss after IVF, decreased pregnancy rates, decreased fertilization, higher gonadotropins requirements, as well as an impaired response to gonadotropins. The cause of a poorer IVF treatment outcome in obese women may be due to poor oocyte quality with subsequent lower fertilization and/or implantation defects caused by a qualitatively poor endometrial milieu. Obesity is also associated with increased problems during pregnancy, such as an increased risk of hypertension; and gestational diabetes.
How can you judge if you are overweight or obese ? In order to do so, you need to measure your BMI, or Body Mass Index . This is an index of your relative "skinniness or fatness", because it factors in your weight as well as your height. Body mass index is calculated with the formula: weight (in kilos) divided by height (in meters) squared. A high BMI indicates obesity.
A standard medical definition of "normal" body weight is a BMI of about 18.5 - 24.9
· A BMI under 18.5 indicates that the person is "underweight"
· A BMI of 25.0 - 29.9 indicates that the individual is "overweight", but not obese
· A BMI over 30 indicates obesity
· A BMI over 40 indicates extreme obesity
If you are overweight, you can enhance your fertility and your chances of having a healthy baby by losing weight . This is why weight reduction should be the first line treatment for obese, infertile women. This needs a multidisciplinary approach to weight management that fosters lifestyle change through proper diet, exercise, behavior modification and stress reduction .
The tragedy, of course, is that this is easy advise to dispense – but very hard to do in real life. No one wants to be obese and losing weight can be really hard to accomplish. Some IVF clinics refuse to treat obese patients; and turn them away unless they can reduce their BMI. I feel this is adding insult to injury. Obese women who are infertile don’t choose to be obese, just as they do not choose to be infertile; and if , after they have tried to lose weight but failed, it’s unfair to withhold infertility treatment from them. Forcing them to wait until they lose weight just causes them to lose even more precious time, and makes a bad situation worse.
If an infertile obese women understands the importance of losing weight; and sincerely tries to do so; but fails to do so even after 6 months of trying, I feel the least we can do is at least help her to have a baby. Improving her fertility may help to improve her self-esteem !

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