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NHS Choices: Behind the headlines   + / -  
last updated: Thu, 31 Jul 2014 10:25:06 GMT

 Wed, 30 Jul 2014 15:19:00 GMT 'Morning sickness' linked to healthier babies

“Morning sickness isn't all bad news: Women battling the condition may have 'healthier, more intelligent babies’,” the Mail Online reports.

The news is based on the results of a systematic review that looked at the effects of “morning sickness”. Health professionals prefer the term “nausea and vomiting in pregnancy (NVP)” because, as many pregnant women can attest, symptoms can occur at any time.

The researchers were interested in whether NVP was associated with better pregnancy outcomes.

The researchers identified 10 observational studies. All 10 reported a protective effect of NPV, such as a reduced risk of miscarriage, birth defects and premature birth. There was also evidence of an association with better foetal growth and improved mental development.

The results of this study may reassure women with NVP that it could be a good sign.

However,  it is difficult to answer exactly why and how NVP may be associated with improved pregnancy outcomes. One hypothesis is that heightened hormonal levels may help the baby; however, they also make the mother feel terrible.

Before pregnant women with NVP get too excited that they are carrying a genius, it’s important to note that the link with intellectual developmental outcomes come from a single, small study – this is hardly conclusive evidence.

 

Where did the story come from?

The study was carried out by researchers from The Hospital for Sick Children, and the University of Toronto, Canada. Funding sources for this study were not reported, but the researchers state that there are no conflicts of interest.

The study was published in the peer-reviewed journal Reproductive Toxicology.

The results of the study were generally well reported in the UK media. However, it should be noted that as the systematic review did not pool the results of the included studies, some of the figures reported in the media are the results of individual studies.

The Daily Telegraph's headline of “intelligent babies” doesn’t seem so conclusive when you realise this is only based on a single, small study including 45 treated and 47 untreated pregnant women with nausea and vomiting, and just 29 pregnant women without.

 

What kind of research was this?

This was a systematic review of cohort and case-control studies that compared rates of any adverse pregnancy outcome (such as miscarriages, preterm delivery, intrauterine growth restriction, major congenital malformations and long-term developmental outcomes) between women who experienced NVP and women who did not.

In this systematic review, the results of the studies were not pooled; instead, the results of each study were described separately.

All the studies in this systematic review were observational. This means that there could be a wide variety of confounding biological, health and lifestyle differences between women and pregnancies associated with NVP and those without, which could explain the results.

 

What did the research involve?

The researchers searched databases of published literature to identify cohort and case-control studies that had compared rates of any adverse pregnancy outcomes between women who experienced NVP and women who did not.

Outcomes searched for included miscarriages, preterm delivery, intrauterine growth restriction (unusually low birthweight) major congenital malformations and long-term developmental outcomes. Some of these studies identified women with NVP by the use of drugs that control these symptoms, such as antiemetics (a type of drug that is used to treat vomiting and nausea).

Data on the relationship between NVP and pregnancy outcomes was then extracted, along with other study characteristics.

 

What were the basic results?

10 studies were included in the review. Some of the studies reported on more than one pregnancy outcome.

No study was included that did not report a protective effect of NVP.

Two cohort studies examined the relationship between NVP and miscarriage. Both studies found that NVP reduced the risk of miscarriage. One US cohort study found that lack of NVP symptoms was associated with increased risk of miscarriage. An Ecuadorian cohort study found that women with nausea only or nausea with vomiting had a significantly decreased risk of miscarriage.

Six studies examined the relationship between NVP and congenital malformations (malformations present from birth).

All of the studies found that NVP reduced the risk of congenital malformations.

One Hungarian case-control study found that mothers of cases with congenital abnormalities were less likely to have had severe NVP than the mothers of population controls without congenital abnormalities.

Three Swedish case-control studies were included: one found that babies born to women who used any antiemetic had a reduced risk of congenital malformations.

One found that meclozine use (an antihistamine that is considered to be an antiemetic) was associated with a reduced rate of congenital malformations.

The final Swedish study found a reduction in the occurrence of congenital cardiovascular defects associated with the use of antihistamines for NVP.

One study was a meta-analysis of 24 studies. It found that antihistamines taken during the first trimester (12 weeks) reduced the risk of major malformations.

One US case-control study found that NVP was associated with a reduced risk of cleft lip with or without cleft palate, and hypospadias (an abnormality of the urethra and penis).

Four studies looked at the relationship between NVP and growth restriction. All three Swedish case-control studies reported on these outcomes. One found that antiemetic drug use was associated with a reduced risk of low birthweight, prematurity and being small for gestational age; another found that meclozine use was associated with reduced risk of preterm birth, low birthweight and short body length; another found that pregnancies exposed to antihistamines for NVP had a reduction in preterm birth, low birthweight and being small for gestational age.

The Hungarian cohort study found that mothers with NVP symptoms had a lower proportion of preterm births.

One study looked at the relationship between NVP and long-term child development. If found that children exposed to NVP performed better on some psychological tests.

 

How did the researchers interpret the results?

The researchers conclude that “the present analysis reveals a consistent, favourable effect of [NVP] on rates of miscarriages, congenital malformations, foetal growth, prematurity and better development outcomes on standard psychological tests”.

The researchers note that this finding may have an impact on other studies – notably, observational studies of drug safety in pregnant women. This is because differing proportions of women with NVP in the exposed and non-exposed groups could affect the results.

 

Conclusion

This systematic review has found that nausea and vomiting of pregnancy is associated with favourable pregnancy outcomes.

All 10 observational studies included in the review reported a protective effect of NVP.

NVP was associated with a reduced risk of miscarriages, congenital malformations and prematurity, and better developmental outcomes.

Beneficial associations were seen, even if women took medication to control their symptoms.

The results of this study may help to reassure women with nausea and vomiting in pregnancy that this may be a good sign – at least for some measures of a healthy, ongoing pregnancy.

Overall, however, due to the small number of observational studies included, the small number of outcomes examined and the uncertain nature of the relationship and possibility of confounding, the review does not prove that NVP will always indicate a healthy pregnancy.

Importantly, it does not prove the opposite – that a pregnancy without nausea and vomiting means a poorer outcome.

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

Morning sickness isn't ALL bad news: Women battling the condition may have 'healthier, more intelligent babies'. Daily Mail, July 30 2014

Morning sickness may mean healthier, intelligent baby. The Daily Telegraph, July 29 2014

Links To Science

Koren G, Madjunkova S, Maltepe C. The protective effects of nausea and vomiting of pregnancy against adverse fetal outcome - A systematic review. Reproductive Toxicology. Published online June 2 2014

 Wed, 30 Jul 2014 11:17:00 GMT Eating more than 5 a day 'brings no extra benefit'

"Eating more than five a day has 'no extra health benefit'," reports The Independent. The paper reports on a review that combined the results of previous research looking at the effect of increasing the amount of fruit and vegetables people eat.

One of the things they specifically wanted to look at was whether there is a dose-dependent effect. The study did find there was a 5% reduction in risk of death on average from any cause for each additional serving of fruit or vegetables a day.

However, a threshold was observed at around five servings a day, after which the risk of death did not reduce further.

This result would appear to contradict a UK study covered by Behind the Headlines in April, which suggested we should be eating seven a day to achieve the maximum benefit.

This earlier study was not included in the new review, so it is unknown what effect its findings may have had on the results.

Many of us struggle to eat at least five a day, let alone seven a day, so the results of both studies reinforce the importance of including lots of fruit and vegetables in our diet.

 

Where did the story come from?

The study was carried out by researchers from Shandong University and Huazhong University of Science and Technology in China, and the National Institutes of Health and Harvard School of Public Health in the US.

It was funded by the National Natural Science Foundation of China and the US National Institutes of Health. No conflicts of interest were reported.

The study was published in the peer-reviewed British Medical Journal (BMJ). This study is open access, meaning it can be accessed free from the journal's webpage.

The results of this study were well reported in the media. BBC News' and The Guardian's reporting of the study was particularly useful, as both included interviews with the researchers involved in the April study on fruit and vegetable consumption.

 

What kind of research was this?

This was a systematic review and meta-analysis of cohort studies.

The review aimed to examine and quantify the potential dose-response relationship (the effect of increasing consumption) between fruit and vegetable consumption and:

  • risk of death from any cause
  • risk of death from cardiovascular disease, such as heart attack or stroke
  • risk of death from cancer

Systematic reviews aim to identify all the evidence related to a specific research question and synthesise the findings from individual studies or reports in an unbiased way.

Meta-analysis is a mathematical technique for combining the results of individual studies.

A systematic review, when performed well, should give the best possible estimate of the true effect of an association between fruit and vegetable consumption and risk of death.

However, this systematic review only included cohort studies, as randomisation of dietary habits is generally not feasible.

Cohort studies may suffer from confounding. As the researchers note, the link between fruit and vegetable consumption and risk of death could be related to people who eat more fruit and vegetables having a generally healthier lifestyle.

 

What did the research involve?

The researchers searched databases of published literature to identify prospective cohort studies that had looked at the association between levels of fruit and vegetable consumption and death (from any cause, cardiovascular causes, or cancer). Some, but not all, studies adjusted or controlled for other risk factors.

Once they had identified relevant trials, the researchers assessed them to see if they were well performed and then extracted data.

The results of all the trials were combined to produce a bottom line on the association between levels of fruit and vegetable consumption and risk of death.

 

What were the basic results?

Sixteen prospective cohort studies including 833,234 people were included in the systematic review. During follow-up periods ranging from 4.6 years to 26 years, there were 56,423 deaths (11,512 from cardiovascular disease and 16,817 from cancer).

Higher consumption of fruit and vegetables was significantly associated with a lower risk of death from any cause. For each extra serving per day of fruit and vegetables, the risk of death from any cause was reduced by 5%.

There was a threshold around five servings of fruit and vegetables a day, after which the risk of death from any cause did not reduce further.

The risk of death from cardiovascular disease also decreased with increasing fruit and vegetable consumption. The risk of death from cardiovascular disease was reduced by 4% for each extra serving per day of fruit and vegetables.

Higher consumption of fruit and vegetables was not appreciably associated with a risk of death from cancer.

 

How did the researchers interpret the results?

The researchers concluded that: "This meta-analysis provides further evidence that a higher consumption of fruit and vegetables is associated with a lower risk of all-cause mortality, particularly cardiovascular mortality."

 

Conclusion

This systematic review of cohort studies has found higher consumption of fruit and vegetables is associated with a reduced risk of death from any cause, with an average reduction in risk of 5% for each additional serving per day.

There was a threshold observed at around five servings per day, after which the risk of death did not reduce further.

Greater fruit and vegetable consumption was associated with decreased risk of death from cardiovascular disease, but higher consumption was not appreciably associated with death from cancer.

As many of the news stories point out, this threshold at around five servings per day is slightly different from the findings of an English study Behind the Headlines covered back in April.

This study concluded benefits were seen in up to seven or more daily portions of fruit and vegetables. But it was not included in the earlier systematic review, as it was published after the search for studies was completed.

The UK study's population was also slightly skewed compared with national averages. People who consumed the most fruit and vegetables in that study were generally older, less likely to smoke, more likely to be women, be of a higher social class and have a higher standard of education.

These considerations aside, both studies emphasise the benefits of eating fruit and vegetables. Find out more about how to get your 5 A DAY.

Analysis by
Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Eating more than five a day has 'no extra health benefit,' claim researchers. The Independent, July 30 2014

Fruit and veg: More than five-a-day 'no effect'. BBC News, July 30 2014

Five a day will do, larger study of fruit and veg intake suggests. The Guardian, July 29 2014

More than five fruit and veg a day won't make you healthier. The Times, July 30 2014

Eating more than five a day 'has no health benefit'. ITV News, July 30 2014

Links To Science

Wang X, Ouyang Y, Liu J, et al. Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies. The BMJ. Published online July 29 2014

 Tue, 29 Jul 2014 11:26:00 GMT Tiny area of the brain linked to fear of the future

"Pea-sized brain hub could shed light on depression," BBC News reports. UK scientists think they have identified part of the brain responsible for feelings of foreboding. This part of the brain, called the habenula, may also be associated with depression.

The headline is based on a small study that used brain scans to look at brain activity in volunteers subjected to a Pavlovian-style series of experiments.

These volunteers were shown a series of abstract images associated with a chance of receiving or losing £1, receiving no outcome, or receiving a painful electric shock. The researchers hoped the volunteers would soon learn which abstract image was associated with the painful electric shock and this would elicit feelings of fear, pessimism and dread – a so-called conditioning response.

The researchers found activity in the habenula region increased when the volunteers were exposed to the "painful" image, suggesting it plays a role in warning the body and the rest of the brain when something bad is likely to happen.

On one level, the habenula appears to fulfil an important function; a warning system may allow us to avoid a potential harm, or at least learn from our mistakes.

The researchers speculate an overactive habenula may be associated with depression and general anxiety disorder – making people feel constantly fearful and concerned about the future.

While interesting, this is still theoretical research. It is difficult to see what current practical implications it has.

 

Where did the story come from?

The study was carried out by researchers from University College London and the University of Cambridge in the UK, the Japanese National Institute for Information and Communications Technology, and the Université de Lausanne, Switzerland. It was funded by the Medical Research Council.

The study was published in the peer-reviewed journal PNAS and has been made available on an open access basis, so it is free to read online.

The news coverage concentrated on the potential of the habenula as a target for the treatment of depression.

The researchers concluded the data in the current study suggest the habenula contributes to the generation of a number of depressive symptoms, such as anhedonia (inability to experience pleasure from activities usually found enjoyable) and aberrant decision making.

However, the current study didn't actually investigate the role of the habenula in depression or similar disorders.

 

What kind of research was this?

This was an experimental study on people that aimed to determine whether activity in a region of the brain called the habenula changes as people associate images with painful electric shocks.

 

What did the research involve?

The researchers recruited 23 people to participate in this study. The participants were shown seven abstract images. After being shown each of the images, one of four outcomes occurred:

  • they won £1
  • they lost £1
  • they received a painful electric shock
  • no outcome

Each of the seven images was associated with either:

  • a 75% chance of a £1 win, 25% chance of no outcome
  • a 25% chance of a £1 win, 75% chance of no outcome
  • a 75% chance of a £1 loss, 25% chance of no outcome
  • a 25% chance of a £1 loss, 75% chance of no outcome
  • a 75% chance of a shock, 25% chance of no outcome
  • a 25% chance of shock, 75% chance of no outcome
  • a 100% chance of no outcome

While the researchers showed the participants the abstract images, they looked at part of the brain called the habenula using a technique called high-resolution functional magnetic resonance imaging (fMRI). fMRI measures brain activity by looking at blood flow.

After this, participants were asked to choose between two abstract images. This confirmed whether participants had associated the images with an outcome.

 

What were the basic results?

As the participants were shown more and more images, activity in the habenula region of the brain increased when images associated with receiving an electric shock were shown.

Activity in the habenula was greatest when an image associated with a shock was shown, and activity was not significantly different to baseline when images associated with a £1 win or loss were shown.

The researchers also found activity in the habenula was significantly different when images associated with a high probability of receiving a shock were compared with images associated with a low probability of receiving a shock.

At the end of the experiment, when participants were asked to choose between abstract images, images associated with electric shocks were least preferred. This demonstrates participants associated these images with receiving a shock.

 

How did the researchers interpret the results?

The researchers concluded their results show that in people, "The habenula encodes the dynamically changing negative motivational value of stimuli that predict primary punishments."

 

Conclusion

This study has found activity in a region of the brain called the habenula changes as people associate images with negative outcomes, in this case electric shocks.

Further research will be conducted to see whether there are any differences in the activity in the habenula in people with depression. If so, this may lead to new avenues for research into new treatments, but this is a long way off.

If you do find your thoughts dominated by feelings of fear and dread about the future, you may require specialist advice. The free and confidential NHS Choices mood self-assessment tool can guide you on whether to seek advice about your mood.

Analysis by
Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Pea-sized region of the brain linked to pessimism. ITV News, July 28 2014

Is your glass half empty? Scientists identify the 'pessimistic' part of the brain, paving the way for new depression treatments. Daily Mail, July 29 2014

'Pea-sized brain hub could shed light on depression'. BBC News, July 29 2014

Links To Science

Lawson RP, Seymour B, Loh E, et al. The habenula encodes negative motivational value associated with primary punishment in humans. PNAS. Published online July 28 2014


 

 
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