“Scientists create new flu vaccine that works against many different strains of the virus,” The Independent reports.

This headline, and several others like it, is based on early stage research into the development of alternative flu vaccine technologies. While the results of this research are promising, they do not mean that a universal flu jab has been developed.

The study used a new technique where two proteins are bound together to form a nanoparticle. These nanoparticles stimulated an immune response to a greater variety of flu strains than the currently available flu jab.

It is important to stress that this work was carried out in ferrets not humans. Ferrets do have biological similarities to humans, at least in the way they respond to flu and the flu vaccine, so this is a genuinely intriguing development.

But it will take several years of further clinical trials to assess whether this technique can lead to a safe and effective ‘universal flu’ vaccine for humans.

Currently, the best bet is to take measures to protect yourself during peak flu season. This includes regularly washing your hands, staying home from work or school if you have the flu and getting a yearly flu jab if you’re at risk of serious complications.

Where did the story come from?

The study was carried out by researchers from the Vaccine Research Center, part of the US National Institutes of Health (NIH) and was supported by the NIH. The lead researcher is now based at Sanofi, a pharmaceutical company that manufactures vaccines.

The study was published in the peer-reviewed journal Nature.

BBC News reports the findings of the study in an appropriate manner. The headline “Universal flu jab 'edges closer'” and the warning that “a vaccine which could defeat all flu was a long way off” properly convey the stage this research is at.

But most other reporting on this study failed to do this. For example, The Independent’s headline “Scientists create new flu vaccine that works against many different strains of the virus” is premature and does not reflect the early stage of technology development that this research is at.

While the work is a step towards a universal vaccine, the technology has not yet been developed and tested to a point at which it could replace the annual flu jab.

What kind of research was this?

This was a laboratory and animal study that investigated a new approach to generating flu vaccines.

Current vaccines are designed to protect against three strains of the flu virus that health experts expect to be widely circulating in the population during any given year.

This current approach is limited by the fact that the annual vaccine may not match the most common strains circulating that year. This approach also means seasonal flu vaccinations must be carried out annually to ‘catch-up’ with any changes in flu strains.

The aim of this study was to develop a technique targeting a protein that is common to a wide variety of flu viruses, thus priming the body to mount an immune response to a broader range of flu strains.

This research is at a fairly early stage, but it does suggest that it may be possible to develop a universal flu vaccine. The technology will need to be tested further in animals. It will then need to be proven to be safe and effective for people during clinical trials before a ‘universal jab’ could be made available.

What did the research involve?

Researchers fused together two proteins – one, called ferritin, which stores iron and occurs naturally in our blood; the other, called haemagglutinin (HA), which is a viral protein responsible for the initial stages of flu infection. It works by attaching the flu virus to the cell it is going to infect.

Individual ferritin proteins naturally come together and form a smooth hollow ball. Researchers thought that fusing ferritin and haemagglutinin would result in a similar sphere with HA spikes, and that the resulting nanoparticle would be recognised by antibodies.

They further thought that when the spheres were injected into animals they would trigger the body to mount an immune response against a range of flu strains.

To test the ability of this ferritin-haemagglutinin nanoparticle to initiate an immune response, researchers first immunised ferrets with either a traditional flu vaccine or the new complex. They measured the HA titres (titres indicate the number of antibodies the body has produced that recognise the HA spike) three weeks later, and compared the titre levels between the two groups.

Researchers then tested the ability of the ferritin-haemagglutinin complex to protect against a range of flu strains. Three groups of ferrets (one immunised with the new complex, one immunised with a traditional flu vaccine and one non-immunised control group) were exposed to a variety of flu strains. The immune response across the groups was then compared.

What were the basic results?

The researchers found that when the ferritin and haemagglutinin proteins were fused together, the proteins self-assembled into a nanoparticle with haemagglutinin spikes sticking out from the core.

When the nanoparticle was exposed to an antibody known to target HA, the researchers found that it bound to the antibody in a similar manner as traditional flu vaccines.

They say this indicates that the newly developed ferritin-haemagglutinin particles resembled the HA spike of the flu virus, which, in theory, could stimulate an immune response against a flu infection.

Three weeks after immunisation, the researchers found that ferrets injected with the ferritin-haemagglutinin nanoparticle had levels of antibodies (antibody titres) that were approximately ten times higher than those seen in the ferrets injected with the traditional flu vaccine.

They also found that a single injection of these nanoparticles produced an immune response similar to two immunisations with a traditional vaccine.

When challenged with different flu strains, the ferritin-haemagglutinin immunised group of ferrets demonstrated an earlier immune response than the control group, and suffered less weight loss than both the traditionally immunised and non-immunised ferrets, which researchers say further demonstrates the protective effect of the new ferritin-haemagglutinin particles.

How did the researchers interpret the results?

The researchers conclude that this new HA-nanoparticle technology “represents a foundation for a new generation of influenza vaccines and could be adapted to create vaccines for a wide variety of pathogens”.

Conclusion

This is promising research that takes us a step closer to developing a universal flu vaccine. Despite headlines suggesting otherwise, no universal jab has yet been developed.

The researchers say that this new particle is capable of enhancing the body’s immune response compared with the currently used flu vaccine, and that the new complex offers protection against a wider variety of flu strains.

It is important to remember that this research is still in its early stages. This technology development may well lead to the generation of a new type of vaccine. However, significant research is still required to move from the current stage to an available universal flu jab.

Until then, the advice for protecting yourself during flu season remains the same:

• Practise good hygiene – wash your hands regularly, clean commonly used surfaces and use tissues when you cough or sneeze.
• Consider getting an annual flu jab if you are at risk of severe flu complications. Groups at high risk for complications include those over the age of 65, pregnant women and people who have a weak immune system or underlying health condition such as a chronic heart or respiratory disease. 

Read more about preventing the spread of flu.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Universal flu jab 'edges closer'. BBC News, May 23 2013

An end to annual flu injections? Scientists develop new 'universal' jab against all strains of influenza which could last a lifetime. Mail Online, May 23 2013

Scientists create new flu vaccine that works against many different strains of the virus. The Independent, May 22 2013

Concept flu vaccine may be breakthrough. Sky News, May 23 2013

Links To Science

Kanekiyo M, Wei C, Yassine HM, et al. Self-assembling influenza nanoparticle vaccines elicit broadly neutralizing H1N1 antibodies. Nature. Published online May 22 2013

"Terrible night's sleep? Blame your mobile phone" is the advice on the Mail Online website, as "exposure to artificial light 'fools' the brain into staying awake."

This – and similar headlines in the Daily Express, The Guardian and Metro newspapers – is based on a recent opinion piece in the journal Nature, which has published a dedicated supplement on the science of sleep.

The opinion piece suggests that the invention of electric light has altered our sleep patterns over the last century. In particular, the widespread use of LED lights, which we rely on to view smartphones, tablets, televisions and laptops screens, is disrupting our sleep.

This, the author suggests, could have potentially serious health consequences, as poorly controlled insomnia can cause both physical and mental health problems.

As an opinion piece, this should not be taken as evidence that light exposure hampers our ability to sleep. However, it does suggest several ways the two may be linked. The piece offers the theory that one causes the other, but these associations have not been directly tested. But given that the author is a specialist in sleep medicine, his opinion cannot simply be dismissed out of hand.

Who wrote the opinion piece?

The editorial was written by Charles Czeisler, a professor of sleep medicine at Harvard Medical School and chief of the division of sleep medicine at Brigham and Women's Hospital in Boston, US.

Over the past 35 years Dr Czeisler has published widely on sleep, the impact of light on sleep, and the effect of restricted sleep on human behaviour and performance.

What arguments are made?

Dr Czeisler suggests that since the invention of electric light, there has been a fundamental shift in our sleep patterns. He argues that light has enabled us to evolve into a "24/7 society", and that many of the features of this transformation – early starting times at work and school, long commutes, high doses of caffeine – lead to us getting insufficient amounts of sleep.

Dr Czeisler's arguments for the link between the increasing use of electric light and disrupted sleep have highlighted several issues.

The biological effect of artificial light

Dr Czeisler argues that exposure to artificial light during the evening and at night could block the effects of brain cells that help promote feelings of sleepiness, as well the "sleep hormone" melatonin.

At the same time, artificial light could also stimulate brain cells associated with alertness.

The combination of these effects could result in many of us feeling much less sleepy in the evening than we would normally.

Time-trends in light use, cost and sleep

Dr Czeisler reports that the cost of generating light dropped dramatically over the last 50 years, which was associated with an increase in the use of artificial light.

At the same time that the use of artificial light increased, reported levels of sleep deficiency also went up. A recent study looking at data in England from 1993 to 2007 found a continual increase in people seeking treatment for sleep disorders.

However, it is important to note that, as with any observational time-trend data, this argument only outlines associations between light consumption and sleep deficiency, and should not be interpreted as there being a causal relationship based on this editorial alone.

Increased use of LEDs

Dr Czeisler suggests that the recent move from traditional incandescent light bulbs to more energy efficient solid-state light-emitting diodes (LEDs) could further disrupt our sleep.

LEDs are commonly used in TVs, computer screens and handheld electronic devices such as tablets. These LEDs are typically rich in shortwave length (blue and blue-green) light, which the cells in our retina are more sensitive to.

He offers the theory that time in front of these blue light-rich screens at night will be more disruptive to our sleep than incandescent lighting.

Interestingly, one of the final discussion points in the editorial is about our ability to control the wavelengths emitted by LEDs. Dr Czeisler suggests that any adverse effect of exposure to these lights at night could be mitigated by replacing blue heavy light with red or orange heavy light in the evenings.

This editorial offers interesting discussion points surrounding the relationship between light – especially evening or nighttime exposure to light – and difficulty sleeping.

What evidence is cited?

Dr Czeisler's article makes reference to several publications, mainly centred around trends in the average number of hours adults and children sleep each night, and the prevalence of the adverse effects of sleep deprivation. As an opinion piece, the overall discussion points are narrative in nature and are not based on any individual piece of research or evidence.

This specific article on its own cannot provide evidence of a direct link between light exposure and sleep deprivation. However, it is not intended to do so. It offers a broad introduction to a series of articles on the topic, and suggests we consider the ways in which technological changes may impact our ability to get a good night's sleep.

Conclusion

It is certainly possible to reduce your exposure to artificial lights. For example, you could dump your smartphone, give away your iPad, banish television from your home, and refuse to work in any job that involves using a computer. But adopting this kind of luddite lifestyle is probably not to most people's tastes.

One proven method of improving your sleep is what is known as "sleep hygiene". This is where you control both physical and environmental factors in order to promote sleep.

Examples of good sleep hygiene include:

• not drinking tea and coffee four hours before bedtime
• avoiding drinking alcohol or smoking before bed
• using thick blinds or curtains, or wearing an eye mask if the early morning sunlight or bright streetlamps affect your sleep
• wearing ear plugs if noise is a problem

Read more advice about sleep hygiene.

If you have persistent insomnia (more than four weeks), contact your GP for advice. You may require more in-depth "sleep training" counselling, often done using cognitive behavioural therapy (CBT) techniques. Alternatively, there may be an underlying condition contributing towards your insomnia.

Read more about the treatment of insomnia.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Peering at bright screens after dark could harm health, doctor claims. The Guardian, May 22 2013

Terrible night's sleep? Blame your mobile phone: How exposure to artificial light 'fools' the brain into staying awake. Mail Online, May 22 2013

How your iPad tablet could mess with a good night's sleep. Metro, May 23 2013

Links To Science

Czeisler C. Perspective: Casting light on sleep deficiency. Nature. Published online May 23 2013

'Bad weather could raise your blood pressure and even kill you,' is the unnecessarily alarmist headline in the Daily Mail. It reports on a large, complex study that looked for any association between changes in weather and blood pressure rates.

The research focused on patients at a blood pressure clinic in Glasgow and looked at two consecutive visits the patients made within a 12-month period. The researchers combined these findings with Met Office weather data from the time of these visits to assess whether changes in patients' blood pressure were related to changes in the weather.

They found that decreases in temperature and sunshine, or increases in rainfall and frost, were associated with a slight increase in blood pressure.

In the longer term, individuals whose blood pressure seemed sensitive to decreases in temperature and sunshine had slight increases in blood pressure. They also seemed to have overall shorter survival than people insensitive to weather changes.

We know that our bodies respond to temperature changes, so it is plausible that temperature could influence blood pressure. But factors other than the weather may have had a role to play in the blood pressure results seen.

It is also important to point out that the minor increases in blood pressure detected by the study could in many cases be compensated for by taking more exercise or improving your diet.

Where did the story come from?

The study was carried out by researchers from the University of Glasgow. One of the study authors was supported by a Wellcome Trust Capacity Strengthening Strategic Award to the Public Health Foundation of India and a consortium of UK universities.

It was published in the peer-reviewed Journal of the American Heart Association.

The quality of the Daily Mail's reporting of this study is mixed. On the negative side, it presents an over-simplistic conclusion that cannot be drawn from the complex analysis used in this study. The claim made in the headline that 'bad weather...can kill you' is needlessly sensationalised.

On the plus side, its story does contain useful advice from a spokesperson from Blood Pressure UK: "Until we can control the weather, we can still rely on more traditional ways of controlling our blood pressure, such as eating more fruit and vegetables, less salt and alcohol, and taking more exercise."

What kind of research was this?

The researchers say that there is growing evidence that outdoor temperature has an influence on blood pressure, with blood pressure being higher in winter and lower in summer.

This is believed to be because the constriction of blood vessels at colder temperatures increases blood pressure. However, it is unclear whether the temperature-related response differs among individuals.

The current study aimed to examine people's individual changes in blood pressure in response to a range of weather patterns. The researchers also wanted to see whether this was predictive of longer term blood pressure control and mortality.

What did the research involve?

The study included 16,010 people from the Glasgow Blood Pressure Clinic (47% male) who had been referred by their GP in order to control their high blood pressure.

Information on the monthly average weather for the west of Scotland was obtained from the UK Met Office. The Met Office has used a consistent method to analyse climate patterns since 1961, and can provide weather for square kilometre grid points across the UK. Information on four aspects of weather was used in the study:

• air frost
• air temperature
• rainfall
• sunshine

Each visit every person made to the Blood Pressure Clinic was mapped to the mean monthly weather of the west of Scotland. Mean monthly measurements for each of the four aspects of weather were ranked from the lowest to the highest measurement, and then split into four equal groups called quartiles. The lowest quartile (Q1) contained the lowest 25% of measurements and the highest quartile (Q4) contained the highest 25% of measurements.

For each person, the researchers looked at pairs of consecutive clinic visits that were at least one month apart but within the same 12-month period. They were interested in pairs of visits where weather either remained constant (both visits in the same weather quartile) or where weather was very different (one visit in the lowest quartile and one visit in the highest quartile). They categorised the weather for these clinic visits as:

• Q1 to Q4, where weather for the first clinic visit was in the lowest quartile and the subsequent visit was in the highest quartile
• Q4 to Q1, where weather for the first clinic visit was in the highest quartile and the subsequent visit was in the lowest quartile
• Qn to Qn, where both the first and the second clinic visits were in the same weather quartile – there was no change in weather patterns

For each individual, the researchers examined changes in their blood pressure and heart rate between the two visits, and looked at how the size and direction of this change (up or down) related to the change in weather.

The researchers used the General Register Office for Scotland to obtain information on deaths among the participants and causes of death. Mortality information was available up to 2011, allowing up to 35 years of follow-up.

Analyses were adjusted for factors known to influence blood pressure (confounders), including:

• age
• smoking
• alcohol
• high body mass index (BMI)
• kidney disease

What were the basic results?

The average age of individuals at their first clinic visit was 51 years, and most were overweight (mean BMI was 28). The average length of follow-up for each person was 6.5 years.

The researchers found that when there was consistent weather between the two clinic visits (Qn to Qn), there was:

• an average 2.1% decrease in systolic blood pressure (the upper figure of a blood pressure measurement) with consistent air frost
• a 2.2% decrease with consistent temperature
• a 1.7% decrease with consistent rainfall
• a 2.2% decrease with consistent sunshine

For change from high to low weather extremes, there was:

• about a 2% increase in systolic blood pressure with a decrease in temperature and sunshine
• no significant change in systolic blood pressure with a decrease in air frost and rainfall

For change from low to high weather extremes, there was:

• a 1.4% increase in systolic blood pressure with an increase in air frost
• a 0.8% increase in blood pressure for an increase in rainfall
• there was no consistent pattern in blood pressure with a change in temperature from low to high 

When the researchers compared the blood pressure changes seen with consistent weather patterns, a change in the weather from the highest to lowest quartile was associated with about a 6% increase in systolic blood pressure when there was a decline in temperature and sunshine, and about a 4% increase in systolic blood pressure when there was a decline in air frost.

Compared with consistent weather, a change from the lowest to highest quartile was associated with 2-6.6% increases in systolic blood pressure for all four weather characteristics assessed.

Looking at longer term changes over five or more years, people whose blood pressure changed when there was a decline in temperature experienced a 2.68mmHg increase in their systolic blood pressure, and a 1.84mmHg increase in their diastolic blood pressure (the lower figure in a blood pressure measurement), compared with people whose blood pressure seemed insensitive to temperature change. 

A similar 1.31mmHg increase in systolic blood pressure and a 1.22mmHg increase in diastolic blood pressure was seen for people who were sensitive to a decline in sunshine.

Looking at survival data, people who were insensitive to temperature or sunlight change seemed to have longer survival than people who were sensitive to a decline in temperature or sunlight.

There were no significant longer term differences in blood pressure or survival between people insensitive to temperature or sunlight change, or in people sensitive to an increase in weather extremes.

How did the researchers interpret the results?

The researchers have concluded that for the first time they have demonstrated the extent of alterations in blood pressure between consecutive clinic visits associated with changes in weather in people with high blood pressure.

They have extrapolated that knowing a person's blood pressure response to weather could help prevent doctors making unnecessary changes to blood pressure medication.

Conclusion

This study has used a complex method of analysis in order to look at how individuals' blood pressure at consecutive visits within a one-year period varied according to changes in the weather.

The study benefits from its large population sample and long follow-up. The blood pressure measurements taken at this specialist clinic are also likely to be reliable.

Our bodies do respond to changes in temperature and it is biologically plausible that temperature can affect our blood pressure. The researchers have adjusted for many factors known to influence blood pressure, such as age, high BMI and kidney disease.

However, it is still difficult to say with certainty that all blood pressure changes seen in people between clinic visits were solely down to changes in the weather. For example, the researchers did not have complete information about the blood pressure medications being used by the patients, or their levels of physical activity. These factors could also be influencing the findings.

Another limitation is that blood pressure would have been recorded inside the clinics and may not be representative of what blood pressure would have been if it had been taken outside, with full exposure to the weather.

The research was conducted in individuals from the Glasgow area and it is difficult to say whether similar responses would be seen in people in other locations, particularly people living in vastly different climates.

Similarly, the study only looked at people with high blood pressure. It is not clear whether people with normal blood pressure also experience similar changes in their blood pressure in response to weather changes.

The individuals in the study seem to have been variably sensitive to different changes in the weather. It is not yet clear exactly how a person's blood pressure treatment could be individualised according to their sensitivity to weather change, and whether this would successfully reduce blood pressure variability.

One final important point to make is that although we have no control over the weather, we can control a wide range of factors that contribute towards high blood pressure, such as:

• the amount of exercise you take
• diet – if your blood pressure is high, you should cut down on salt, saturated fat and sugar, and eat plenty of fruit and vegetables
• quitting smoking, if you smoke
• the amount of alcohol you drink

Read more about proven lifestyle changes you can make to reduce your blood pressure risk.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Bad weather could raise your blood pressure and even kill you. Daily Mail, May 21 2013

Chilly days can kill by raising blood pressure. Daily Express, May 22 2013

Links To Science

Aubinière-Robb L, Jeemon P, Hastie CE, et al. Blood Pressure Response to Patterns of Weather Fluctuations and Effect on Mortality. Hypertension. Published online May 6 2013

“Mothers’ diets may harm IQs of two babies in three,” warns The Independent. The newspaper reports on its front page that iodine deficiency is widespread among pregnant women.

Iodine is recognised to play a role in the healthy development of the baby’s brain and nervous system while in the womb and the World Health Organization recommends that pregnant women eat iodine-rich foods.

Severe lack of iodine is one of the leading causes of brain damage in the developing world. But a new study, reported in most of the media today, suggests that even mild-to-moderate iodine deficiency during pregnancy may be associated with poorer cognitive function in the child.

In this large study, the iodine levels of pregnant women were measured, and their child’s IQ at age eight and reading ability at age nine were tested.

The researchers found that children of women who didn’t get enough iodine were more likely to be in the lowest quartile for verbal IQ, reading accuracy and reading comprehension. However, there was no significant difference in overall IQ.

A study of this kind has limitations, for example the fact that it relies on measurements being taken at a single point in time. Also, although the researchers adjusted for many factors that may have influenced the relationship (for example, parental lifestyle and socioeconomic factors), the study cannot prove a direct cause and effect relationship between a mother’s iodine consumption during pregnancy and her child’s cognitive ability. It is also not clear whether the differences seen in the children’s verbal and reading skills would translate into ‘real-world’ problems for these children.

Nevertheless, the study does highlight the need for pregnant women to get enough iodine during pregnancy.

Where did the story come from?

The study was carried out by researchers from the University of Surrey and the University of Bristol. No specific funding was reported for the current study, but researchers were supported by the Waterloo Foundation, the Commission of the European Communities, the US National Oceanographic and Atmospheric Administration and Wassen International. The latter is a company that makes and sells iodine supplements. However, none of these organisations had any role in how the study was conducted or how the collected data was interpreted.

This study used information taken from a much larger ongoing cohort study known as the Avon Longitudinal Study of Parents and Children (ALSPAC), which is looking at the health outcomes of children born during the 1990s. The ALSPAC study is supported by the Medical Research Council, the Wellcome Trust and the University of Bristol.

The study was published in the peer-reviewed medical journal The Lancet.

The media reporting is generally representative of the study, although the Mail Online headline writers got into a serious muddle. When they first published the story they used the headline “Drinking organic milk in pregnancy is 'vital for the baby's future brain power'". This was then changed later in the day – "Drinking organic milk in pregnancy could be harming baby’s IQ".

Neither claim is supported by this study. The study did not assess women’s dietary iodine intake from different sources. So it is not possible to say how many women drank organic milk and whether those who did were more likely to be in the iodine deficient group.

What kind of research was this?

The researchers say that the World Health Organization considers iodine deficiency to be “the single most important preventable cause of brain damage” worldwide. Iodine has a role in regulating the thyroid gland, and thyroid hormones have a role in brain and nervous system development. 

The researchers say that changes to dairy farming after the 1930s increased the amount of iodine in milk in the UK. After this and due to the reduction in cases of goitre associated with thyroid problems in the UK it was considered that iodine intake in the UK was sufficient.

However, some more recent UK studies have suggested that mild iodine deficiency may be quite common among adolescent schoolgirls and pregnant women.

The current study used data collected from participants in the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort study to see whether there was an association between pregnancy iodine levels and child cognitive performance. The researchers speculated that women with lower iodine levels during pregnancy would have children with poorer cognitive outcomes.

What did the research involve?

The ALSPAC cohort was eligible to all pregnant women in southwest England with a due date between April 1991 and December 1992.

A total of 14,541 pregnant women were enrolled and 13,988 of their children survived for at least 12 months.

The researchers selected 1,040 women for whom they could measure iodine in the first trimester of pregnancy (up to 12 weeks) and their child’s IQ when they were eight years old.

Iodine was measured in a single urine sample. Urinary iodine levels are said to be a good indicator of iodine levels in the body as 90% of ingested iodine is excreted into the urine. However, the results would have been more accurate if the researchers had been able to measure iodine based on 24-hour urine collection.

To try to reduce the impact of this issue, the researchers looked at the iodine-to-creatinine ratio, which is said to be a good way to get a more accurate iodine measurement. The researchers defined adequate iodine as an iodine-creatinine ratio of 150 micrograms or more per litre. Iodine deficiency was sub-categorised as mild-to-moderate (50 to 150) or severe (less than 50).

Child IQ at the age of eight was assessed using a validated scale (the Wechsler Intelligence Scale for Children). At the age of nine psychologists also assessed children’s reading speed, accuracy and comprehension. 

The researchers looked at the association between pregnancy iodine status and IQ at the age of eight and reading at the age of nine. They adjusted analyses for a wide range of confounders including:

• mother’s age
• mother’s ‘parenting score’ (assessed by looking at cognitive stimulation of the baby, parental education and socioeconomic status)
• home environment, including baby’s emotional and cognitive environment
• family adversity
• stressful events during pregnancy
• infant birth weight and prematureness
• breastfeeding history
• maternal smoking and alcohol intake
• other dietary factors during pregnancy, including intakes of omega-3 fatty acids and iron

What were the basic results?

The researchers found that, overall, the women in the study had an average (median) urinary iodine concentration of 91 micrograms per litre, and average iodine-to-creatinine ratio of 110 micrograms per litre. About two-thirds of women in the study (67%) were iodine deficient in pregnancy. None of the women was using an iodine supplement.

Compared with mothers with adequate pregnancy iodine, those with iodine deficiency were significantly younger and less educated, but had less exposure to stressful life events in pregnancy.

Compared with children of women with adequate pregnancy iodine levels and after adjustment for confounders, children of women with iodine deficiency were at significantly higher risk of:

• having a verbal IQ score in the lowest quartile (odds ratio 1.58, 95% confidence interval (CI) 1.09 to 2.30)
• having a reading accuracy score in the lowest quartile (odds ratio 1.69, 95% CI 1.15 to 2.49)
• having a reading comprehension in the lowest quartile (odds ratio 1.54, 95% CI 1.06 to 2.23)

However, there was no significant association between pregnancy iodine deficiency and performance IQ or overall IQ score – only verbal IQ. There was also no significant association between iodine deficiency and reading score or number of words read per minute – only reading accuracy and comprehension.

How did the researchers interpret the results?

The researchers say that their results demonstrate the importance of having adequate iodine intake during early pregnancy. They say that the results “emphasise the risk that iodine deficiency can pose to the developing infant, even in a country classified as only mildly iodine deficient”. The researchers consider iodine deficiency during pregnancy to be an important public health issue that needs attention.

Conclusion

This is a valuable study that demonstrates that in this subsample of a large cohort of pregnant women in the UK, the majority had inadequate iodine levels during pregnancy.

They also found that this deficiency was associated with poorer verbal IQ in their children at the age of eight, and reading accuracy and comprehension at the age of nine.

The study benefits from its relatively large sample size, from the fact that it followed participants up over time and from the fact that it adjusted for extensive confounding factors.

However, there are some limitations to this study:

• As the researchers say, several 24-hour urine collections would have been the ideal way to measure iodine levels, rather than a single measure, but this would be impractical in a large-scale study.
• It would also be useful to continue to reassess the children’s IQ and reading performance at different time points, particularly as the associations were only found for certain measures of IQ and reading ability. Related to this, it is also unclear what impact these differences in verbal IQ and reading accuracy and comprehension would have had on the children’s learning and school performance. Children’s IQs are not thought to be fixed for life but can change over time.
• Studies in other population samples from other countries would be valuable.

The researchers note that a randomised controlled trial assessing the effect of iodine supplementation in pregnant women on child cognitive ability in areas with mild-to-moderate iodine deficiency would be valuable. They say that they hope to run such a trial in the UK, as current evidence from trials in this area is weak. 

Overall, the study highlights the need for pregnant women to obtain sufficient iodine during pregnancy. The World Health Organization recommends that pregnant and breastfeeding women consume 250 micrograms of iodine a day.

Dietary sources of iodine include dairy products and fish. Pregnant or breastfeeding women who are unable or unwilling to eat these types of iodine-rich dietary sources may need supplements.

If you are pregnant or breastfeeding and are concerned about your iodine levels, speak to your GP or midwife before taking supplements. Supplements will not be suitable for every woman.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.

Links To The Headlines

Mothers' diets may harm IQs in two-thirds of babies. The Independent, May 22 2013

Iodine deficiency 'may lower UK children's IQ'. BBC News, May 22 2013

Women who drink organic milk in pregnancy could be harming their baby's IQ. Mail Online, May 22 2013

Enough iodine vital in pregnancy – study. The Guardian, May 22 2013

Links To Science

Bath SC, Steer CD, Golding J, et al. Effect of inadequate iodine status in UK pregnant women on cognitive outcomes in their children: results from the Avon Longitudinal Study of Parents and Children (ALSPAC) . The Lancet. Published online May 22 2013