Women working in irregular shifts are likely to experience reduced fertility and greater menstrual disruption than those working in regular shifts, according to a new research.

The team of researchers led by Dr Linden Stocker and Dr Ying Cheong, Southampton's Princess Anne Hospital, assessed the impact of non-standard working schedules, which included night and mixed shifts, on the reproductive outcomes of 119,345 women.

The study found that women who worked only nights had 29 percent increased rate of miscarriage.

Women who worked in rotational shifts had an 80 percent higher rate of subfertility - meaning that they were unable to conceive within a year compared with those working regular hours.

Women working out of the typical 9 am to 6 pm schedule also had a 33% higher rate of menstrual disruption, the study found.

"We don't fully understand why shift workers have an increased risk of certain diseases but obviously shift work impacts on your biological functioning, your psychological functioning and your social functioning", Dr Stocker was quoted as saying by an English news website.

The researchers, however, have asked women not to jump to a conclusion and quit jobs as the study is still in the preliminary stage.

Working odd hours is often linked to sleep loss, decreased exercise and poorer diet thereby drastically disrupting a woman's body clock.

In a previous study, researchers had claimed that women who had worked in nights shifts for 30 or more years are twice as likely to suffer from breast cancer.

Irregular bedtimes in early childhood have been linked with low scores in reading, maths in both boys and girls, a study has suggested.

The study authors looked at whether bedtimes in early childhood were related to brain power in more than 11,000 seven year olds, all of whom were part of the UK Millennium Cohort Study (MCS).

The research drew on regular surveys and home visits made when the kids were 3, 5, and 7, to find out about family routines, including bedtimes.

The authors wanted to know whether the time a child went to bed, and the consistency of bed-times, had any impact on intellectual performance, measured by validated test scores for reading, maths, and spatial awareness.

And they wanted to know if the effects were cumulative and/or whether any particular periods during early childhood were more critical than others.

Irregular bedtimes were most common at the age of 3, when around one in five children went to bed at varying times. By the age of 7, more than half the children went to bed regularly between 7.30 and 8.30 pm.

Children whose bedtimes were irregular or who went to bed after 9 pm came from more socially disadvantaged backgrounds, the findings showed.

When they were 7, girls who had irregular bedtimes had lower scores on all three aspects of intellect assessed, after taking account of other potentially influential factors, than children with regular bedtimes. But this was not the case in 7 year old boys.

Irregular bedtimes by the age of 5 were not associated with poorer brain power in girls or boys at the age of 7. But irregular bedtimes at 3 years of age were associated with lower scores in spatial awareness in both boys and girls, suggesting that around the age of 3 could be a sensitive period for cognitive development.

Girls who had never had regular bedtimes at ages 3, 5, and 7 had significantly lower reading, maths and spatial awareness scores than girls who had had consistent bedtimes. The impact was the same in boys, but for any two of the three time points.

The authors point out that irregular bedtimes could disrupt natural body rhythms and cause sleep deprivation, so undermining the plasticity of the brain and the ability to acquire and retain information.

They wrote that sleep is the price that people pay for plasticity on the prior day and the investment needed to allow learning fresh the next day.

They added that early child development has profound influences on health and wellbeing across the life course, therefore, reduced or disrupted sleep, especially if it occurs at key times in development, can have important impacts on health throughout life."

Researchers including an Indian origin have shed some light on why aspirin benefits some people and not others.

Researchers at Duke Medicine developed a blood-based test of gene activity that has been shown to accurately identify who will respond to the therapy.

The study showed that the new gene expression profile not only measures the effectiveness of aspirin, but also serves as a strong predictor of patients who are at risk for heart attack.

The Duke researchers enlisted three groups of participants - two of healthy volunteers and one comprised of patients with heart disease seen in outpatient cardiology practices.

The healthy volunteers were given a dosage of 325 mg of aspirin daily for up to a month; the heart disease patients had been prescribed a low dose of aspirin as part of their treatment.

Blood was then analyzed for the impact of aspirin on RNA expression and the function of platelets, which are the blood cells involved in clotting.

The RNA microarray profiling after aspirin administration revealed a set of 60 co-expressed genes that the researchers call the "aspirin response signature," which consistently correlated with an insufficient platelet response to aspirin therapy among the healthy subjects as well as the heart disease patients.

The researchers also examined the aspirin response signature in another group of patients who had undergone cardiac catheterizations. They found the signature was also effective in identifying those patients who eventually suffered a heart attack or died.

Deepak Voora, M.D., assistant professor of medicine at Duke and lead author of the study, said that the aspirin response signature can determine who is at risk for heart attack and death.

He said that there is something about the biology of platelets that determines how well we respond to aspirin and we can now capture that with a genomic signature in blood.

The study has been published in the online edition of the Journal of the American College of Cardiology.

A urine test can now determine whether a transplanted kidney recipient is in the process of rejecting the donated organ, as well as identifying who is at risk of rejection several weeks and even months before symptoms appear.

By measuring just three genetic molecules in a urine sample, the test accurately diagnoses acute rejection of kidney transplants, the most frequent and serious complication of kidney transplants, says the study`s lead author, Dr. Manikkam Suthanthiran, the Stanton Griffis Distinguished Professor of Medicine at Weill Cornell Medical College and chief of transplantation medicine, nephrology and hypertension at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

"It looks to us that we can actually anticipate rejection of a kidney several weeks before rejection begins to damage the transplant," Dr. Suthanthiran says.

"It looks to us that we can actually anticipate rejection of a kidney several weeks before rejection begins to damage the transplant," Dr. Suthanthiran says.

The test may also help physicians fine-tune the amount of powerful immunosuppressive drugs that organ transplant patients must take for the rest of their lives, Dr. Suthanthiran, whose laboratory developed what he calls the "three-gene signature" of the health of transplanted kidney organs, said.

"We have, for the first time, the opportunity to manage transplant patients in a more precise, individualized fashion. This is good news since it moves us from the current one-size-fits-all treatment model to a much more personalized plan," he says, noting that too little immunosuppression leads to organ rejection and too much can lead to infection or even cancer," the researcher said.

Such a test is sorely needed to help improve the longevity of kidney transplants and the lives of patients who receive these organs, says study co-author Dr. Darshana Dadhania, associate professor of medicine and medicine in surgery at Weill Cornell Medical College and associate attending physician at New York-Presbyterian Hospital.

The study is published in The New England Journal of Medicine (NEJM).

Staying mentally active by reading books or writing letters helps protect the brain in old age, says a new American study.

The study, published in Neurology, says performing mental challenges leads to slower cognitive decline. It adds weight to the idea that dementia onset can be delayed by lifestyle factors, BBC reported.

In the study by the Rush University Medical Center in Chicago, 294 people over the age of 55 were given tests that measured memory and thinking, every year for about six years until their deaths.

They also answered a questionnaire about whether they read books, wrote letters and took part in other activities linked to mental stimulation during childhood, adolescence, middle age, and in later life.

After death, their brains were examined for evidence of the physical signs of dementia, such as brain lesions and plaques.

The study found that after factoring out the impact of those signs, those who had a record of keeping the brain busy had a rate of cognitive decline estimated at 15 percent slower than those who did not.

Robert Wilson, of the Rush University Medical Center, who led the study, said the research suggested exercising the brain across a lifetime was important for brain health in old age.

"The brain that we have in old age depends in part on what we habitually ask it to do in life. What you do during your lifetime has a great impact on the likelihood these age-related diseases are going to be expressed," Wilson told BBC.

Commenting on the study, Simon Ridley, head of research at Alzheimer`s Research UK, said there was increasing evidence that mental activity may help protect against cognitive decline. But the underlying reasons for this remained unclear.

"By examining donated brain tissue, this study has shed more light on this complex question, and the results lend weight to the theory that mental activity may provide a level of `cognitive reserve`, helping the brain resist some of the damage from diseases such as Alzheimer`s," he told BBC.