Fertility Falls with Weight Gain

Overweight women are significantly more likely to experience fertility problems, according to a study published in the journal Human Reproduction last week. Obesity is defined in adults as having a body mass index (BMI) above 30. The study found that for every BMI unit above 29, the probability of achieving pregnancy was reduced by four per cent. Dr Jan Willem van der Steeg of the Academic Medical Centre in Amsterdam, who led the study, told the BBC that the findings were 'worrying' in light
of increasing obesity levels in the UK and elsewhere. 'We think that women should be informed about their lower pregnancy chances due to their overweight', he said in a statement, adding: 'We hypothesise that losing weight will increase the chance to conceive without treatment'.
BMI is a measure of body fat based on height and weight. The BMI categories used clinically are normal (18.5-24.9),overweight (25-29.9) and obese (greater than 30). Last month, new guidelines from the British Fertility Society recommended recently that severely obese women, who are under 37 and therefore not in danger of thwarting their reproductive years, should have their fertility treatment deferred until they have lost weight. However at the time some critics voiced concerns that BMI was not a good indicator of body fat in all women, such as those who have a lot of muscle. The researchers examined 3,000 'sub-fertile' women - those who have had at least one year of unprotected sex without conceiving - in the first study of its kind to look at the link between BMI and pregnancy chances in a large group of women who have no obvious reasons for infertility. At the top end of the scale, very obese women (with a BMI of over 35) were found to be 26-43 per cent less likely to conceive than women within an average BMI range of 21-29.
One theory is that leptin - a hormone that regulates appetite and energy expenditure and is secreted in fatty acids - may affect hormone levels in obese women. 'It is possible that obese women may have disturbed hormone levels, which decrease the chances of successful fertilisation and implantation', said Dr van der Steeg, who is convinced that rising levels of
obesity is a primary factor in the increasing numbers of couples seeking infertility treatment.

Zero Sperm Counts & Genetic Links

What has become evident at our Centers over the last several years is that our ability to diagnose and successfully treat severe male infertility problems has surpassed our ability to understand the basic causes of these problems. In the recent past, it was considered that nearly 20% of men with extremely low or "zero" sperm counts had no known medical reason for their fertility problems. Most recently, major advances in molecular biology and genetics have provided the "reasons" for severe infertility (very low or zero sperm counts) in many men whose fertility problems were previously poorly understood. We now know that 20-30% of men with such low (under 10 million/ml) or zero sperm counts have a now identifiable genetic cause for their problem. While we are now able to assist many, many men previously thought to be "hopelessly" infertile achieve pregnancy, it remains very important to not only treat these men, but to provide such couples with genetic information related to the problem causing the low or zero count. This is important because many of these genetic characteristics may potentially be passed along to children conceived with the help of modern male infertility treatments. Genetic disorders that would previously not have been able to be "passed along" due to the male's infertility are now being retained in the "gene pool" as a result of new procedures that overcome most of these previously untreatable male conditions.
Y chromosome deletions can be a contributing factor in male infertility. Only men have a Y chromosome and it is passed from father to son. The Y chromosome contains genes that direct an embryo to develop into a male. While there are few genes on the Y chromosome, included are genes that are important for male fertility.Microdeletions are missing regions of DNA that are so small they can't be detected through normal chromosome analysis. Instead, labs use advanced techniques like polymerase chain reaction (PCR) to detect whether the regions are present or missing. Sperm production is affected when there are microdeletions on the long arm of the Y chromosome in regions called AZF (for azoospermic factor). Genetic testing looks at three AZF regions. If a deletion is found, the prognosis depends on the amount of missing DNA and the region in which it is missing. Y chromosome microdeletions are the second most common genetic reason that men have a low sperm count or lack sperm. (Klinefelter's syndrome is the most common reason.) Currently, there are no other known health problems that come from having a Y chromosome microdeletion other than infertility.
Incidentally, we were the first in India to offer this test. You can order this test from our homepage at http://www.iwannagetpregnant.com/myctest.shtml
Wishing our bloggeurs a fertile new year!

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Sperm Penetration Assays (SPA, "Hamster Tests")

There have been many attempts made to develop a Laboratory test that will accurately predict the ability of a human sperm to fertilize a human egg. Dr. Aitken and his group many years ago demonstrated a correlation between sperm movement characteristics and sperm fertilizing ability as evaluated by the zona pellucida-free hamster egg penetration test. In this test, the species specific barrier to penetration (not fertilization) is removed from the ova (eggs) of the hamster. These oocytes are then exposed to prepared sperm from the man being tested. One of the most widely used accessory tests in the evaluation of advanced sperm function, the fusion between human sperm and the hamster oocyte (egg) is nearly identical to that occuring with the human egg. Fusion with the vitelline membrane of the oocyte is normally initiated by the healthy sperm's plasma membrane that lies over a special section (equatorial segment) of the sperm head in a sperm that has prepared itself for normal fertilization. This test relies upon the ability of sperm that are tested in the laboratory to undergo the necessary reactions to fertilize an egg. Because the sperm prepare themselves in a slightly different manner in the laboratory than in the body, false negatives (fail in the hamster test but normally fertilize the partner's human egg) have been reported. This test may be used as a screen to asist in determining which men may need the assistance of "ICSI" fertilization. There is some feeling that if a man's sperm are able to penetrate the hamster eggs in the laboratory, there is a higher likelihood that his sperm will ultimately be able to fertilize a human egg if so exposed. This test is not uniformly accepted, due to the high false negative (no penetration of the hamster egg, but wife gets pregnant anyway) rate and the sometimes seen false positive (penetrates the hamster egg but does not fertilize human eggs in vitro) rate of this test. Global experience has been that good performance in the hamster test can provide some limited reassurance of the likelihood that a man's sperm will be able to achieve fertilization if given the chance. If men fail the hamster test, most centers rely upon in vitro fertilization with ICSI. This protocol has provides excellent success rates in men whose sperm function remains questionable. It should be noted that most men that fail the hamster test, are able to achieve normal fertilization with ICSI.