Researchers Dispute IUDs’ Alleged Link to Higher Infertility Risk
Intrauterine devices, an inexpensive and effective birth-control technique widely used around the world, fell into disfavor in the United States in the 1970s because of severe problems associated with one such device, the Dalkon Shield.
Now a study concludes that other IUDs are safe and do not, as some had feared, lead to infertility.
The new study, led by Dr. David Hubacher of Family Health International, a research group in Durham, N.C., was conducted in Mexico, where IUDs are widely accepted.
The researchers studied 1,895 women at three public hospitals in Mexico City between 1997 and 1999. Nearly two-thirds of the women were seeking fertility treatments, while the rest were pregnant for the first time. Some of the women had used IUDs, while others had not.
By comparing the women, the researchers concluded that there was no increased risk of infertility associated with IUDs, they reported in the Aug. 23 New England Journal of Medicine.
Most of the women used the copper IUD, a T-shaped piece of plastic wrapped in copper wire. The device slowly releases copper, preventing pregnancy by irritating the uterine lining and altering fluid in the uterus and fallopian tubes.
The study was sponsored by the National Institutes of Health and the U.S. Agency for International Development. Only about 1% of U.S. women using contraceptives employ IUDs, but they are used by about 106 million women worldwide.
Gene Variant Signals Risk of Cardiac Death
Finnish researchers have identified a new gene variant that doubles the risk of sudden cardiac death, or heart attacks, in young men by making blood stickier and thus more likely to clot. Testing for the gene in men with a family history of heart disease could reduce the death rate by permitting treatment with blood-thinning agents to reduce the likelihood of clot formation, the researchers said.
Dr. Jussi Mikkelson and colleagues at the University of Tampere Medical School in Tampere, Finland, performed autopsies on 700 white Finnish men who suffered violent or sudden out-of-hospital deaths. They reported in the Aug. 21 issue of Circulation: Journal of the American Heart Assn. (https://circ.ahajournals.org) that the gene variant, called HPA-2 Met, was 2.2 times as common among those who suffered sudden cardiac death.
Research Links Autismto 4 Chromosomes
An international team of researchers has identified regions on four chromosomes that appear to be linked to autism, further supporting the idea that the disorder has a strong genetic link.
Team members studied more than 150 pairs of siblings in which one child had the disorder and the other did not. They reported in the September issue of American Journal of Human Genetics that they found extremely strong evidence of a link to regions on chromosomes 2 and 7, and strong evidence of a link to regions on chromosomes 16 and 17.
Chromosome 7 has previously been linked to speech disorders, and some previous studies have linked it to autism as well.
Researchers will now focus on chromosomes 7 and 2 in an effort to identify the specific genes involved, said Dr. Ed Cook of the University of Chicago, but that effort may require study of as many as 500 sibling pairs.
More information about the international consortium is available at https://www.well.ox.ac.uk/~maestrin/iat.html.
Obesity Increases Riskof Pancreatic Cancer
As if fat people didn’t already have enough problems, a new study shows that obesity nearly doubles the risk of pancreatic cancer. The good news, however, is that the same study shows that moderate physical exercise can reduce the risk almost back to normal. Pancreatic cancer is the fifth-leading cause of cancer deaths in the United States.
Epidemiologist Dominique S. Michaud and her colleagues at the Harvard School of Public Health analyzed data from two large public health studies that included 46,648 men and 117,041 women. All were free of cancer when they entered the studies. The team found 350 cases of pancreatic cancer in the follow-up.
Close analysis of the cases revealed that subjects who were the most obese had a 72% increase in the risk of pancreatic cancer compared to those of normal weight, researchers reported in the Aug. 22 Journal of the American Medical Association (https://jama.ama-assn.org). Surprisingly, the tallest patients in the study had an 81% increase in risk.
But the researchers also found that walking or hiking for an hour and a half each week lowered the risk in the obese people by 50%.
Researchers already knew that diabetes increases the risk of pancreatic cancer. Michaud speculated that the same factors were at work in obesity, but the link to height remains a mystery.
Change of Oils in Diet Can Combat Diabetes
Postmenopausal women who eat vegetable fats or polyunsaturated fats instead of saturated fats can lower their risk of diabetes by 16% to 22%, researchers report in the September Diabetes Care.
Epidemiologist Katie A. Meyer at the Harvard School of Public Health and her colleagues found that substituting vegetable fats for animal fat in the diets of women aged 55 to 69 lowered their diabetes risk by 22%, while substituting polyunsaturated fats for saturated fats lowered in by 16%.
Recent studies have shown that losing 5% to 7% of body weight and exercising 30 minutes a day five times a week can reduce the risk of developing diabetes by 55%.
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Medical writer Thomas H. Maugh II can be reached at thomas.maugh@latimes.com.
