Chronic stress caused by the Covid-19 pandemic will lead to a generation of babies being born smaller, scientists claim
- British researchers pooled data from more than one million women and children
- Stress during pregnancy was significantly linked to a lower birth weight
- Being born small can cause long-term problems, including for health
Chronic stress caused by the Covid-19 pandemic may lead to a wave of babies being born smaller, scientists claim.
Researchers analysed eight studies involving more than 8,200 pregnant women and over a million children.
They found stress during pregnancy was significantly linked to a lower birth weight – defined as a weight of less than 5lbs 8oz for a full-term baby.
Being born small can cause long-term problems, having been linked to poor school performance, being overweight as an adult and an earlier death.
Being pregnant in itself can be stressful, without the addition of a global pandemic that is still wreaking havoc.
Concerns about money, job security, child support housing or family matters can all lead to ‘chronic stress’ and are expected to worsen as a result of the coronavirus.
Chronic stress caused by the Covid-19 pandemic will lead to a wave of smaller babies being born, scientists claim (stock)
The average newborn weighs about 8lbs and anything under 5.8lbs is considered underweight.
Low birthweight babies struggle to feed, gain weight, fight off infections and can develop breathing difficulties.
As they grow older, they are also known to face a greater risk of suffering problems such as diabetes and cardiovascular disease.
In developing countries, poor growth in the womb is one of the major causes of low birthweight.
In Western nations, low birthweight is often associated with prematurity – a baby born earlier than 37 weeks gestation.
Low birthweight is often due to prematurity as a result of high maternal age.
Smoking, medically unnecessary caesarean sections and fertility treatments can also all increase the risk of a baby being born with a low birthweight.
An example of this was how the 2008 financial crisis hit Spain, with the prevalence of babies of being born at a low birth weight rose by around two per cent.
The impact of chronic emotional stress on human growth has been investigated by scientists for decades.
Professor Barry Bogin, a biological anthropologist at the University of Loughborough, was behind the new research with a colleague in Spain.
He reviewed several previous studies to predict how Covid-19 may impact the birth weight of the next generation.
Each study was a ‘biocultural’ study — one that considers how social and emotional factors interact and impact human biology.
Writing in the American Journal of Human Biology, Professor Bogin and co-author Dr Carlos Varea said the coronavirus may see an expecting mother go from ‘happy and joyful to fearful and concerned’.
Based on the findings, the pair predict that ‘it will take two or more generations’ to understand exactly how the Covid-19 will affect babies to come.
However, they wrote: ‘One may hypothesise for the immediate future there will be a global rise in maternal emotional stress and a decline in birth weight.’
The academics uncovered a ‘significant’ link between antenatal stress exposure and increasing rates of low birth weight.
One study published in 2012 measured levels of the stress hormone in saliva in 488 mothers in the Philippines.
Mothers-to-be with higher cortisol levels in the evening often went on to have baby boys who weighed less. But girls were not affected as much.
Another study looked at the babies of 3,360 women who were in some way exposed to the 9/11 terrorist attack of the World Trade Center in New York City, such as being inside a building that collapsed, or living in the area.
THERE WON’T BE A COVID-19 BABY BOOM BECAUSE PARENTS WILL WORRY ABOUT MONEY, SCIENTISTS SAY
There will not be a Covid-19 baby boom straight after the pandemic because couples will be too concerned about their money, experts predict.
Throughout history, spikes in deaths due to war, disease or famine have been followed by wave of pregnancies as countries get back to normal.
People thought this might have after the Covid-19 because couples were spending more time together and might have more sex.
But births are likely to decline after the crisis because the impact of lockdowns will be so long-term, Italian researchers say.
Professor Arnstein Aassve and colleagues at Bocconi University, Milan drew the conclusion that post-Covid fertility will plausibly decline due to economic uncertainty and increased childcare burdens.
Raising a child costs money, and therefore it may seem unfeasible to adults who are struggling with money due to job losses.
This was the experience of the 2008 Great Recession, when overall fertility declined, particularly in countries that had the strongest economic downturns.
A high level of uncertainty about the future would also likely put couples off having a baby.
In high-income countries, new parents often rely on childcare. But during the pandemic, children have been forced back into the homes due to nursery and school closures.
In low- and middle-income countries, fertility has declined in recent decades due to trends such as urbanization and more women getting jobs.
This is unlikely to be fundamentally reversed by economic setbacks caused by Covid-19, the paper said.
However, difficulties in accessing family planning services could cause a spike in unintended pregnancies, which was seen after the West African Ebola crisis.
The scientists’ paper was published in July by Science Magazine, the peer-reviewed journal of the American Association for the Advancement of Science.
They found that ‘all types of direct exposure at the site and PTSD were associated independently with low birth weight’ in births two years after the event.
Professor Bogin and Dr Varea concluded the ‘fundamental message from this review is maternal stress lowers birth weight’.
One of the studies analysed was their own, which identified a similar trend during the 2008 to 2014 financial crisis in Spain.
The number of small babies born to first-time mothers increased from 5.12 per cent in 1996 to 6.87 per cent in 2008.
And among women who were already mothers, the prevalence of low-birth-weight babies increased from 3.96 per cent to 5.2 per cent.
Professor Bogin said: ‘We reported a decline in birth weight across virtually all maternal social-economic groups in Spain in the years leading up to, and especially, during the financial crisis.
‘Our findings are supported by studies reporting reduced birth weight in Portugal, Iceland, Japan, and Greece during the 2008 banking system crisis, which was a global financial pandemic.’
Professor Bogin and Dr Varea explain in their commentary how chronic stress can cause biological changes in the body, altering hormone levels and cell behaviour.
Maternal stress and its impact on the baby may also be due to indirect actions such as a poor diet, addictive behaviour such as smoking and failing to go to antenatal appointments.
The experts defined ‘chronic stress’ as insecurity related to money, housing, social support. It includes worry about job loss, loss of benefits, loss of a partner, or loss of housing.
Talking about stress due to Covid-19, Professor Bogin and Dr Varea said: ‘Fear of pandemic disease spreads as fast and as deep as the disease itself.
‘The fear plays‐out in in many ways, from extremes of paranoia and violence, to xenophobia, closed borders, economic lockdowns, and social distancing.
‘The fear pervades every level of society. The fear causes emotional stress. Chronic emotional stress—from insecurity that lasts for months or years—has biological impacts on people.’
The researchers noted recent events prove the pandemic is causing emotionally-driven behaviour.
For example: ‘During the first week of April, 5G cellular communication towers in Birmingham, Liverpool and Melling, UK were burned by people claiming that 5G technology is the cause of Covid-19.’
They wrote: ‘Pregnant women, their foetuses, and young people of all ages will suffer if exposed to chronic, toxic emotional stress.
‘Chronic toxic stress takes a toll on human health, including the physical growth of people, as much as do food shortages and infection.’
The consequences of low birth weight include an increased risk of poor learning and school performance, psychological problems and reduced adult earnings.
In relation to health, it could lead to infection, adult obesity, diabetes, heart disease, and, on average, an earlier age at death, the researchers noted.
The paper will feature in a forthcoming special issue on the Covid-19 pandemic in the American Journal of Human Biology.
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