THURSDAY, Nov. 29 (HealthDay News) -- A mammogram isn't the easiest medical exam to endure, sometimes painful and often embarrassing to the woman.

And that's thought to be one potential reason why mammography rates have declined in women over age 40, after decades of steady increase, according to researchers at the U.S. National Cancer Institute.

That decrease has alarmed cancer experts, who believe the X-ray exam is the best way to detect breast cancer early.

"Mammograms are not perfect tests, but they currently are the most effective test available," said Dr. Michael Naughton, a breast cancer oncologist at the Washington University School of Medicine's Siteman Cancer Center in St. Louis.

"I think the best evidence that mammograms save lives is the falling mortality rate since we've been using them for early detection," added Naughton, who's also a member of the American Society of Clinical Oncology.

The death rate for breast cancer began to fall in 1989, dropping by about 1.6 percent each year through 1995, according to the American Cancer Society. Between 1995 and 1998, the drop in rates picked up even more speed, declining about 3.4 percent each year.

Overall, between 1990 and 2002, death rates from breast cancer declined an average of 2.3 percent annually for all women, with larger reductions in women younger than 50, according to cancer society statistics.

The drop in breast cancer rates coincided with an increase in the use of mammography to detect tumors in the breast.

Between 1987 and 2000, the use of mammography dramatically increased in women over the age of 40, from 39.1 percent to 70.1 percent, according to the National Cancer Institute. Rates stabilized between 2000 and 2003, but, by 2005, rates were 4 percent lower than they were in 2000 -- 66 percent versus 70 percent.

Doctors are concerned that if the use of mammography continues to decline, the success they've had in saving lives from breast cancer will begin to falter.

Breast cancer mortality has continued to decline, even as mammogram rates stabilized and then fell, but Naughton believes there would be a lag before the reduced use of mammograms would begin to show itself in more cancer deaths.

"If we stopped doing mammograms today, we wouldn't see an increase in the mortality rate for four or five years," Naughton said. "But survival is linked to early detection. The earlier the stage of cancer when we find it, the more likely the woman will survive."

Mammograms typically involve two low-dose X-rays of each breast. The technician taking the X-rays places each breast between two panels, pressing to get a clear picture and causing discomfort in some women.

Mammograms make it possible to detect tumors that can't be felt. The screening also can find microcalcifications, or tiny deposits of calcium, that sometimes indicate the presence of breast cancer, according to the National Cancer Institute.

The U.S. government recommends that women begin regular mammography screenings at age 40, receiving an examination every one to two years. Women at higher-than-average risk due to family history or other factors should talk with their doctor about whether they should begin regular screenings earlier than 40.

No studies have yet shown why the mammography rate has declined, but cancer experts have their guesses.

America's health-care system is one culprit in the eyes of Dr. Aman Buzdar, a professor of medicine and deputy chairman of the department of breast medical oncology at the University of Texas M.D. Anderson Cancer Center, in Houston.

With dozens of health insurance plans offering different benefits, women can become confused about when they need to receive a mammogram, Buzdar said.

"In the countries where the mammogram rate is high, we find there is a single payer who notifies patients that they are due for their mammogram," he said.

That leads to another possibility -- that women simply forget about undergoing the screening.

"A number of patients, it just falls off their radar," Buzdar said.

Discomfort and embarrassment also are believed to play a part, both Buzdar and Naughton said. "Physical discomfort is definitely a discouraging factor," Naughton said.

Finally, women might be avoiding the screening, because they just don't want to hear they might have cancer.

"They just don't want to hear the news, even if it's better to hear it when they can't feel anything," Buzdar said. "But detecting the disease early is in your best interest. You can successfully beat the cancer if it's detected early, versus just hoping that there's nothing there."

More information

To learn more about mammography, visit the U.S. National Library of Medicine.

WEDNESDAY, Nov. 28 (HealthDay News) -- If your new baby is keeping you awake at night, take note: A first-of-its-kind study suggests that sleep deprivation after giving birth may limit a new mother's ability to shed those pregnancy-related pounds.

It's not clear why there may be a link between sleep loss and lack of weight loss. Still, the possibility of a connection is intriguing, said study lead author Erica P. Gunderson, an investigator with the Kaiser Permanente Division of Research in Oakland, Calif.

"Getting enough sleep may be as important as a healthy diet and physical activity to returning to pre-pregnancy weight," Gunderson said.

According to the study authors, scientists have linked low amounts of sleep to obesity, heart disease and diabetes. But there's been little research into the connection between sleep and pregnancy and weight.

For the new study, the researchers looked at the weights and sleep patterns of 940 women who enrolled in a study in Massachusetts during early pregnancy from 1999 to 2002.

A year after giving birth, 124 of the women retained at least 11 pounds of the weight they had gained during pregnancy. After the researchers adjusted the statistics to take into account such factors as family income, they found that women who slept five hours a day six months after giving birth were more than three times likelier to keep weight on compared to women who slept seven hours.

Sleeping six, seven or eight hours a day didn't appear to raise a woman's risk of keeping on weight. "Basically, the women who were sleeping fewer hours did not lose as much weight as women who slept several more hours," Gunderson said.

The study findings, by researchers at Kaiser Permanente and Harvard Medical School/Harvard Pilgrim Health Care, were published in the November issue of the American Journal of Epidemiology.

It might seem that people who sleep less would actually lose more weight, because they'd spend more time burning calories while awake. But the study suggests the opposite, Gunderson said, perhaps because people become hungrier due to lack of sleep.

Also, she added, "If you're awake more, you may have more opportunities to eat."

Claire D. Brindis, a professor of pediatrics at the University of California, San Francisco, said her own experience of giving birth to two children taught her about how stress, sleep and weight are all connected.

"Having lived this, it's partly that you're more tired, and you feel you need food to keep you energized," she said. "And when you're stressed, you feel like you can reward yourself with food. It creates a sense of comfort."

Gunderson said the next step is to understand what women who sleep less after pregnancy have in common. Doctors can then "target women who may not be getting enough sleep and find ways to support them," she said.

More information

To learn more about sleep, visit the National Sleep Foundation  .

WEDNESDAY, Nov. 28 (HealthDay News) - A gene long linked to suppressing the growth of cancer may also play a vital role in human reproduction, researchers report.

In experiments with mice, researchers found that females lacking the p53 gene had fewer embryos implanted in the uterus, less chance of becoming pregnant, and when they did conceive, they had fewer offspring. A lack of p53 did not affect the fertility of male mice, however.

"This is an amazing new function for a gene that everybody thought they knew what it did," said lead researcher Arnold J. Levine, a professor at the Institute for Advanced Study, in Princeton, N.J. "This is a gene that is not only watching over us so that we cannot get cancer, but it watches over our genome so that we can develop normally," he added.

The report appears in the Nov. 29 issue of Nature.

The p53 gene responds to a variety of stresses, such as radiation damage, in ways that allow it to protect cells against cancer, Levine explained. However, he added, "We found, quite by surprise, the normal function of p53 in the uterus of mice."

In order for embryos to implant in the uterus, a cytokine called LIF (leukemia inhibitory factor) is essential, and "p53 turns on the gene that makes LIF," Levine explained. "It's estrogen plus p53 making LIF that allows implantation."

In mice without the p53 gene, males are fine, but females only infrequently implant eggs and "the litter sizes go way down," Levine said. However, when these mice were given an injection of LIF, they reproduced normally.

Whether this finding has implications for humans isn't clear, Levine said. "We do know that humans require LIF in the uterus, but whether p53 has the same function in humans is something we are working on," he said.

Levine believes that p53 could play a part in human reproduction and infertility, but "there must be other factors as well," he said.

Defects in p53 are extremely rare in humans. "There are about 250 families in the United States that have defects in the p53 gene, a condition called Li-Fraumeni syndrome. This syndrome predisposes patients to cancer at an early age," Levine said.

One expert believes the finding could have clinical implications.

"Some humans show genetic variation in the amount of p53 they can produce and how well some of these variants of p53 function," said Colin Stewart, a principal investigator at the Institute of Medical Biology in Singapore and author of an accompanying editorial in the journal.

One study suggested that some women who have difficulty in getting pregnant tend to have the less efficient form of p53, Stewart noted.

"This may be why they have problems becoming pregnant, because the less efficient form of p53 does not make sufficient amounts of LIF that are necessary to get the embryo to attach to the wall of the uterus," Stewart said.

Drugs are currently being developed that would either improve the way p53 works or block the action of defective forms of p53, Stewart said.

"Some of these drugs may turn out to be useful in helping women conceive by improving the function of p53 in the uterus. Others may turn out to be possible contraceptives by blocking p53's function in the uterus," he added.

More information

For more information on p53, visit the National Center for Biotechnology Information.

TUESDAY, Nov. 27 (HealthDay News) -- Black American women and Chinese women who ate foods high on the glycemic index -- which measures the effect of carbohydrates on blood glucose levels -- were at increased risk for developing type 2 diabetes, two new studies found.

One of the studies also found that eating more cereal fiber may be associated with a reduced risk of type 2 diabetes in black American women.

In one study, Boston University School of Public Health researchers examined data on more than 40,000 black American women who filled out a food questionnaire in 1995. Every two years through 2003, the women provided updates about their weight, health and other information.

During those eight years of follow-up, 1,938 of the women developed type 2 diabetes.

Women who ate high-glycemic index foods or ate a diet with a high glycemic load were more likely to develop diabetes. Women who ate more cereal fiber were less likely to develop diabetes.

"Our results indicate that black women can reduce their risk of diabetes by eating a diet that is relatively high in cereal fiber," the study authors wrote. "Incorporating fiber sources into the diet is relatively easy: A simple change from white bread (two slices provides 1.2 grams of fiber) to whole wheat bread (two slices provides 3.8 grams of fiber) ... will move a person from a low fiber intake category to a moderate intake category, with a corresponding 10 percent reduction in risk."

In the second study, researchers from Vanderbilt University Medical Center in Nashville, Tenn., followed more than 64,000 Chinese women for an average of five years. During the study, 1,608 of the women developed diabetes.

High consumption of carbohydrates increased the risk of diabetes. Women who consumed the most carbohydrates (about 337.6 grams per day) had a 28 percent greater risk of developing diabetes than those who consumed the least (about 263.5 grams per day).

Women who had high glycemic index diets and who ate more food staples such as bread, noodles and rice also had an increased risk. For example, those who ate more than 300 grams of rice per day were 78 percent more likely to develop diabetes than those who ate less than 200 grams of rice per day.

"Given that a large part of the world's population consumes rice and carbohydrates as the mainstay of their diets, these prospective data linking intake of refined carbohydrates to increased risk of type 2 diabetes mellitus may have substantial implications for public health," the researchers concluded.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about type 2 diabetes.