(Press-News.org) London, 9 July 2013: Shift work, which encourages sleep deprivation and patterns of activity
outside the circadian rhythm, has been associated with a greater risk of ill health and loss of
well-being in some (but not all) studies.(1) However, little is known about the effects of shift
work on reproductive health and fertility.
Now, a study reported today at the annual meeting of ESHRE, by Dr Linden Stocker from the
University of Southampton, UK, indicates that working shift patterns is associated with an
increased risk of menstrual disruption and subfertility.
The study is a meta-analysis of all studies on the subject published between 1969 and January
2013. It compares the impact of non-standard working schedules (including night-shift work and
mixed-shifts) with that in women not working shifts. The end-points were early reproductive
outcome parameters, including menstrual dysregulation, female fertility and miscarriage rates.
The study, which included data on 119,345 women, found that those working shifts (alternating
shifts, evenings and nights) had a 33% higher rate of menstrual disruption than those working
regular hours (odds ratio 1.22, statistically significant) and an 80% increased rate of subfertility
(OR 1.80, statistically significant).(2)
Women who worked only nights did not have a statistically increased risk of menstrual
disruption or difficulty conceiving, but they did have an increased rate of miscarriage (OR 1.29),
although this increased risk of miscarriage was not observed in women who worked nights as
part of a shift pattern.
The investigators describe their findings as "novel", but in keeping with other studies (which
found adverse effects in later pregnancy). "If replicated," they said, " our findings have
implications for women attempting to become pregnant, as well as for their employers".
On the implications of the study Dr Stocker said: "Whilst we have demonstrated an association
between shift work and negative early reproductive outcomes, we have not proven causation. In
humans, the long-term effects of altering circadian rhythms are inherently difficult to study. As a
proxy measure, the sleep disruption demonstrated by the shift workers in our study creates
short- and long-term biological disturbances. Shift workers adopt poor sleep hygiene, suffer
sleep deprivation and develop activity levels that are out-of-sync with their body clock.
"However, if our results are confirmed by other studies, there may be implications for
shift workers and their reproductive plans. More friendly shift patterns with less
impact on circadian rhythm could be adopted where practical - although the optimal
shift pattern required to maximise reproductive potential is yet to be established."
In noting that only some reproductive outcomes were affected by shift work, Dr Stocker
reported that the underlying biological disturbances involved in reproductive difficulties "are
complex and not the same across all the disease processes". "Indeed," she said, "it is probable
that completely different causes underlie menstrual dysfunction, miscarriage and subfertility.
This may explain why the effects of different types of shift work are seen in some groups of
women, but not others."
She added that one possible explanation for the overall findings is that the disruption of
circadian rhythm can influence the biological function of "clock genes", which have been shown
to be associated with changes in biological functions.
###
Abstract 193, Tuesday 9 July 17.15 BST
Do working schedules influence early reproductive outcomes - a metaanalysis
Notes
1. Most studies have concentrated on the association between shift work and cardiovascular
risk factors, with an emphasis on circadian rhythm, disturbed activity patterns, reduced social
support, psychological stress, stress, unhealthy behaviour (smoking, diet, alcohol, exercise), and
metabolic changes (cholesterol, blood pressure). Some studies have found a higher association
in shift workers, but results tend to be varied and the studies of inconsistent methodology.
Meta-analysis (as in this study) provides a way of pooling the data and applying a consistent
methodology.
2. Menstrual disruption was defined as a cycle which deviated from the normal 28
days; either a short menstrual cycle (32 days).
Shifts included all women who worked at any time other than a standard day-time schedule.
This could include night shifts, evening shifts, split shifts or rotating shifts.
* When obtaining outside comment, journalists are requested to ensure that their contacts are
aware of the embargo on this release.
For further information on the details of this press release, contact:
Christine Bauquis at ESHRE
Mobile: +32 (0)499 25 80 46
Email: christine@eshre.eu
Women working shifts are at greater risk of miscarriage, menstrual disruption and subfertility
2013-07-09
ELSE PRESS RELEASES FROM THIS DATE:
Egg banking for social reasons
2013-07-09
London, 9 July 2013: Egg freezing as insurance against age-related infertility is a growing trend in
many countries. Women who bank oocytes for use at some time in the future hope to buy a
little time in their search for a suitable partner.
However, a study from one of Europe's largest centres in reproductive medicine suggests that
many of those banking eggs believe they will never use them - even though they still recognise
the experience as "positive". The majority of those who did (and did not) freeze their eggs
wished they had done so at an earlier age.
The study ...
Research demonstrates the influence of temporal niches in maintaining biodiversity
2013-07-09
By studying rapidly evolving bacteria as they diversify and compete under varying environmental conditions, researchers have shown that temporal niches are important to maintaining biodiversity in natural systems. The research is believed to be the first experimental demonstration of temporal niche dynamics promoting biodiversity over evolutionary time scales.
The temporal niches – changes in environmental conditions that occur during specific periods of time – promoted frequency-dependent selection within the bacterial communities and positive growth of new mutants. ...
Tumor-suppressor Protein Gives Up Its Secrets
2013-07-09
Genetic mutations aren't the only thing that can keep a protein called PTEN from doing its tumor-suppressing job. Johns Hopkins researchers have now discovered that four small chemical tags attached (reversibly) to the protein's tail can have the same effect, and they say their finding may offer a novel path for drug design to keep PTEN working.
In a report published on July 9 in the journal eLife, the Johns Hopkins scientists describe how a cluster of four phosphate groups, first found 13 years ago to bind to PTEN's tail, controls its activity.
"Now that we know ...
What warring couples want: Power, not apologies, Baylor study shows
2013-07-09
The most common thing that couples want from each other during a conflict is not an apology, but a willingness to relinquish power, according to a new Baylor University study.
Giving up power comes in many forms, among them giving a partner more independence, admitting faults, showing respect and being willing to compromise. The study is published in the Journal of Social and Clinical Psychology.
"It's common for partners to be sensitive to how to share power and control when making decisions in their relationship," said researcher Keith Sanford, Ph.D., an associate professor ...
Scientists image vast subglacial water system under West Antarctica's Thwaites Glacier
2013-07-09
AUSTIN, Texas — In a development that will help predict potential sea level rise from the Antarctic ice sheet, scientists from The University of Texas at Austin's Institute for Geophysics have used an innovation in radar analysis to accurately image the vast subglacial water system under West Antarctica's Thwaites Glacier. They have detected a swamp-like canal system beneath the ice that is several times as large as Florida's Everglades.
The findings, as described this week in the Proceedings of the National Academy of Sciences, use new observational techniques to address ...
Bird vaccine for West Nile Virus
2013-07-09
University of British Columbia researchers have developed a vaccine that may halt the spread of West Nile Virus (WNV) among common and endangered bird species.
WNV, a mosquito borne pathogen, arrived in North America in 1999 and is now endemic across the continent. In 2012 alone, WNV killed 286 people in the United States, and 42 people have died from the virus in Canada since 2002. There is currently no effective vaccine against WNV infection in humans or birds.
Common birds such as crows, ravens and jays, and endangered species such as the Greater Sage-Grouse and ...
Double-barreled attack on obesity in no way a no-brainer
2013-07-09
In the constant cross talk between our brain and our gut, two gut hormones are already known to tell the brain when we have had enough to eat. New research suggests that boosting levels of these hormones simultaneously may be an effective new weapon in the fight against obesity.
Dr Shu Lin, Dr Yan-Chuan Shi and Professor Herbert Herzog, from Sydney's Garvan Institute of Medical Research, have shown that when mice are injected with PYY3-36 and PP, they eat less, gain less fat, and tend not to develop insulin-resistance, a precursor to diabetes. At the same time, the researchers ...
Graphene on its way to conquer Silicon Valley
2013-07-09
The unique properties of graphene such as its incredible strength and, at the same time, its little weight have raised high expectations in modern material science. Graphene, a two-dimensional crystal of carbon atoms packed in a honeycomb structure, has been in the focus of intensive research which led to a Nobel Prize of Physics in 2010. One major challenge is to successfully integrate graphene into the established metal-silicide technology. Scientists from the University of Vienna and their co-workers from research institutes in Germany and Russia have succeeded in fabricating ...
Technologies for monitoring remaining leukemia after treatment may help predict patient outcomes
2013-07-09
(WASHINGTON, July 9, 2013) – New evidence suggests that using advanced genetics technologies to monitor for remaining cancer cells after treatment may soon become an effective tool to inform treatment decisions and ultimately predict patient outcomes for patients with a particularly aggressive form of acute lymphocytic leukemia (ALL). Study results were published online today in Blood, the Journal of the American Society of Hematology (ASH).
Approximately 25 to 30 percent of all adults with ALL, the second most common type of acute leukemia, have what is known as Philadelphia ...
Are clinical trial data shared sufficiently today?
2013-07-09
Ben Goldacre, research fellow at the London School of Hygiene and Tropical Medicine, says we need all the evidence to make informed decisions about medicines.
The lack of progress on transparency has been startling, he writes. Current estimates suggest that around half of all trials for the treatments being used today have gone unpublished; and that trials with positive results are twice as likely to be published.
There is legislation mandating greater transparency – such as the law requiring trial results to be posted on the website clinicaltrials.gov – but the published ...