WEDNESDAY, Nov. 21 (HealthDay News) -- Researchers have identified the chemical pathway by which a mother's smoking before and after pregnancy might reduce her daughter's fertility by as much as two-thirds.

Cigarette smoking during pregnancy has been shown in retrospective studies to affect the fertility of a woman's offspring, but this is the first study to offer an explanation of the biology behind the effect, the Canadian scientists claim.

A team at the Samuel Lunenfeld Research Institute at Mount Sinai Hospital in Toronto investigated the impact of polycyclic aromatic hydrocarbons (PAH), a byproduct of smoking, on mouse fertility.

Researchers injected three groups of female mice with a low-dose mixture of PAH: One group received PAH before conception and again when they were providing milk for their pups; one group received PAH only before conception; and the third group received PAH only during lactation. A fourth control group did not receive PAH but were mated at the same time as the others. The total amount of PAH given to each mouse over the three-week injection cycle was equivalent to 25 packs of cigarettes, according to the researchers. The exposed mice did not have fewer pups in their own litters, but when researchers investigated the number of eggs in their female offspring, they found about 70 percent fewer follicles available to produce eggs.

"Mothers, mice in this case, exposed to PAHs -- environmental pollutants found in cigarette smoke, car exhaust, smoke produced by fossil fuel combustion, as well as in smoked food --before pregnancy and/or during breast-feeding, but not during pregnancy, can cause a reduction in the number of eggs in the ovaries of their female offspring by two-thirds. This limits the window in which the daughter will be able to reproduce," explained lead researcher Dr. Andrea Jurisicova.

Further analysis indicated that the effects of PAHs on the number of follicles in female offspring were mediated through a receptor that affects the expression of a gene that makes a protein that causes cells to die. The researchers then demonstrated similar effects in human ovarian tissue transplanted into immunocompromised mice.

Jurisicova described the process: "Toxic compounds were injected under the skin of mice and were picked up by the bloodstream and carried throughout the body until they reached the ovaries. Once at the ovaries, they passed through the cell membrane and bound to the receptor. When this happens, it activates the receptor, which then enters the cell nucleus. The receptor then finds a specific DNA sequence that turns on the gene, which accumulates and eventually kills the eggs."

"This study now is providing a chemical pathway, which is very nice," said Dr. Norman Edelman, consultant for scientific affairs with the American Lung Association. The new data provides biological support for epidemiological results, such as the previously observed reduction in fertility among daughters of smoking women, he added.

Whether the news will have an impact on a woman's decision to smoke is another question, said Edelman.

"If we do our job right and these results get good press, this data could remind women of what they are doing to their unborn fetuses," Edelman said.

Another expert noted this latest finding adds to a growing body of evidence that shows a strong connection between smoking and fertility.

"I think it is an interesting study, but it doesn't add much new. Other studies have shown similar outcomes. The theory is that smoking could affect the follicles or the fallopian tubes," said Dr. Amos Grunebaum, director of obstetrics at New York Weill Cornell Medical Center, in New York City. "We have known for many years that smoking affects fertility on many levels."

"The key is women should quit smoking before they are thinking of getting pregnant," Grunebaum said.

The Canadian researchers did offer some good news in their report, published in the Dec. 3 edition of the Journal of Clinical Investigation. Injecting resveratrol in the mice who were exposed to PAH prevented the reduction in egg follicles in their offspring. Resveratrol is a naturally occurring antioxidant found in wine and grape skins. However, that reversal of damage does not mean that women who smoke can counter the effects with a nutritional supplement or a glass of red wine, the researchers stressed.

"We have found that oral consumption of resveratrol as a food supplement, at least in mice, is not effective, as levels of resveratrol do not reach sufficient amount in the bloodstream to provide protection," Jurisicova said.

Although the findings do not define the length of time between quitting smoking and healthier fertility in offspring, Jurisicova noted that previous studies have shown that women who smoke have better results with in vitro fertilization one year after they quit smoking. The mice in the current study conceived up to two weeks after their final PAH injection, which is approximately equivalent to three menstrual cycles in women.

The effect of a mother's cigarette smoking is not limited to her female children. A study published in the Jan. 1 issue of the American Journal of Epidemiology suggested that the male offspring of mothers who smoke have lower sperm counts.

There is still more research to be done, Jurisicova noted.

"We hope to continue studying the female offspring to see if they enter the mouse version of menopause earlier than mice whose mothers were not exposed to PAHs," Jurisicova said. "We also hope to study if their reduced fertility passes on to subsequent generations, and if the granddaughters are predisposed to similar problems."

More information

Need to quit smoking? Visit the U.S. Surgeon General or the National Institutes of Health.

FRIDAY, Nov. 9 (HealthDay News) -- As many as 25 percent of men over age 45 admitted to hospital with acute urinary retention (AUR) die within a year, a death risk comparable to that of patients with a broken hip, a new study says.

AUR, the sudden inability to pass urine, is a medical emergency. The condition is often a progression of benign prostatic hyperplasia, an enlargement of the prostate that can interfere with normal urine flow. AUR may also be linked to the presence of other disorders such as diabetes and high blood pressure, according to background information in the study, which was published Nov. 9 by BMJ Online First.

The study authors, from the University College London and London School of Hygiene and Tropical Medicine, analyzed data on more than 176,000 English men over the age of 45 who were hospitalized for treatment of a first episode of AUR between 1998 and 2005.

The researchers found that one in seven of the men with spontaneous AUR (no evidence of precipitating factors other than benign prostatic hyperplasia), and one in four with precipitated AUR, died within one year.

The risk of death increased with age and the presence of other health problems (comorbidity). About half the AUR patients over age 85 with comorbid conditions died within a year after being hospitalized.

The researchers calculated that the overall one-year death risk for men admitted to hospital with AUR was two to three times higher than for the general male population. Among AUR patients ages 45 to 54, the death risk was nearly 24 times higher.

AUR patients may benefit from urgent multidisciplinary care to identify and treat comorbid conditions early, the researchers concluded.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about prostate enlargement.

FRIDAY, Nov. 16 (HealthDay News) -- Checking on fetal heart-rate patterns can offer insight into how a child's nervous system will develop through its toddler years, a U.S. study finds.

Johns Hopkins and U.S. National Institutes of Health researchers checked fetal heart rate and variability -- the degree to which heart rate increases and decreases within a specific time period -- six times from 20 weeks through 38 weeks of gestation in 137 women with normal pregnancies.

When the children born to the women were between 24 months and 36 months old, the researchers assessed their mental, motor and language abilities.

Greater variation in fetal heart rate at about 28 weeks gestation predicted better performance on a standardized developmental exam at age two, and better language skills at 30 months, said the study, which is published in the November/December issue of the journal Child Development.

Fetuses that had more rapid gains in heart rate variation beginning at 20 weeks gestation had quicker progression through childhood mental, motor and language milestones than children who had slower fetal gains in heart-rate variations.

According to the researchers, the findings suggest that the basis of individual differences in children's development begins during gestation.

"Further demonstration that these and other indicators of fetal functioning supply important information about the developing nervous system will enrich our understanding of the importance of the prenatal period of life," study lead author Janet DiPietro, a professor in the department of population, family and reproductive health, and associate dean for research at Johns Hopkins Bloomberg School of Public Health, said in a prepared statement.

"In turn, such knowledge can contribute to the formation of strategies focused on improving prenatal functioning in these arenas by facilitating pregnancy well-being. However, since current obstetric care already routinely evaluates heart rate patterning as an indicator of fetal distress, pregnant women do not need to seek out additional information about their baby's heart rate from their providers," DiPietro said.

More information

The U.S. Centers for Disease Control and Prevention has more about child development.

FRIDAY, Nov. 9 (HealthDay News) -- Women taking oral contraceptives are at a slightly increased risk for developing cervical cancer, but a decade after stopping the pill even this very small risk disappears, a new British study suggests.

However, that finding doesn't change the recommendation for women to continue getting screened for cervical cancer, experts say.

"This is good news," said lead researcher Dr. Jane Green, an epidemiologist in the Cancer Epidemiology Unit at the University of Oxford. "We have been able to estimate the lifetime risk of cervical cancer for women on the pill and find it's really quite small," she said.

"The small increase in cervical cancer we see in women who are taking oral contraceptives starts to fall once pill use stops and has really gone away by 10 years after stopping use," Green said.

"The pill has many other benefits, including reducing the risk of other cancers, such as ovarian cancer and womb cancer," Green added.

The report is published in the Nov.10 issue of The Lancet.

In the study, Green and her colleagues from the International Collaboration of Epidemiological Studies of Cervical Cancer collected data on almost 16,600 women with cervical cancer and more than 35,500 women without cervical cancer. These women had participated in a total of 24 studies.

Green's team confirmed that the risk of cervical cancer among women who use oral contraceptives does increase over time. But this increase in risk is very small -- women who take contraceptives for five years or more have only about twice the risk compared with women who never took the pill.

In absolute terms, that means that a 20-year-old woman living in a developed country who uses an oral contraceptive for 10 years increases her odds of developing cervical cancer by age 50 from 3.8 cases per 1,000 women (without Pill use) to 4.5 per 1,000 women after using oral contraception. In less developed countries, where access to cervical cancer screening is more limited, that risk rises from 7.3 to 8.3 cases per 1,000 women, the researchers estimated.

Similar risk was seen for invasive and localized cancer and in women who have the human papillomavirus (HPV), which causes about 70 percent of all cervical cancers, Green noted.

Although the risk for cervical cancer associated with the Pill is small, Green advised women to still be screened for the disease. "Screening for cervical cancer is effective," she said. "The advice is to go for regular screenings."

Eventually, Green hopes that the vaccination against the human papillomavirus will go a long way to preventing many cases of cervical cancer.

One expert agreed that the findings showed the risk for cervical cancer from oral contraceptives was very small.

"This is reassuring news for women," said Dr. Peter Sasieni, from the Wolfson Institute of Preventive Medicine at Queen Mary University of London and author of an accompanying journal comment. "There is really a minimal risk from oral contraceptives, and that risk disappears fairly soon when you stop taking them," he said.

"When making a decision about what from of contraception to use, women shouldn't worry about cervical cancer," Sasieni concluded. "It's not an issue," he said.

However, he believes that taking oral contraceptives is another good reason to get screened regularly for the disease. "By going for regular screenings, a women can reduce her risk by 80 percent," Sasieni said.

Another expert agreed that women shouldn't worry about the Pill and cervical cancer risk.

"I don't think women are basing their decision of which form of contraception to use on the risk for cervical cancer," said Debbie Saslow, director of breast and gynecologic cancer at the American Cancer Society. "People who want to use oral contraceptives should not be alarmed over the slight increase in cervical cancer risk," she said.

However, women -- whether they take oral contraceptives or not -- should be getting regular cervical cancer screening, Saslow said.

More information

For more on cervical cancer, visit the American Cancer Society  .