Pregnant women can reduce the risk of premature birth by getting out in the sunshine during early pregnancy, a new study suggests.
Researchers at the University of Edinburgh found pregnant women exposed to the least natural sunlight in Scotland had a 10 per cent greater risk of a premature birth.
For now, the link between sunshine exposure and premature birth is without a conclusive explanation, but will be looked into further in future studies.
Sun exposure is an ‘important environmental variable’ that has risks and benefits for human health, researchers at the University of Edinburgh report – but less is known about the effects of sun exposure on pregnancy duration and preterm birth
THE THREE TRIMESTERS
0 to 13 weeks
Begins on the first day of a woman’s last menstrual period.
14 to 26 weeks
27 to 40 weeks
A premature baby is delivered before 37 weeks of your pregnancy
‘The role of sunlight is an exciting new avenue for research into preterm birth prevention,’ said study author Dr Sarah Stock at Edinburgh’s MRC Centre for Reproductive Health.
‘This study is important because it provides further data reminding us that sunlight as health benefits as well as risks.’
Dr Stock told MailOnline that the ‘number one theory’ to explain the link is that sunlight causes the release of substances from the skin that relax blood vessels, which helps a healthy pregnancy to establish in the womb.
‘Studies in adults have shown that sunlight reduces blood pressure, as a result of nitric oxide release from the skin,’ she explained.
‘Our early research with pregnant women suggest exposure to components of sunlight affect blood flow to the womb.’
Sunlight also directly contributes to vitamin D production, which helps with the development of an unborn baby’s bones, teeth, kidneys, heart and nervous system.
Of course, excessive exposure to sunlight can damage the skin, but the team claim the benefits of reducing blood pressure far outweigh the risk of developing skin cancer.
‘It is all about balance,’ said Dr Stock. ‘Women should definitely still avoid sunburn which we know is harmful.
‘However our research supports the idea that complete avoidance of sun exposure may also have effects on health.’
For the study, Dr Stock and her co-authors analysed maternity care data for nearly 400,000 mothers and more than 500,000 babies born after 24 weeks of pregnancy.
(A baby born at 24 weeks – which is late on in the second trimester – have around a 50 per cent chance of surviving, according to University of Utah Health.)
Complications caused by preterm birth – defined as babies born alive before 37 weeks of pregnancy – are the leading cause of death in children under five-years-old (stock image)
Maternity records of all single live births in Scotland between 2000 and 2010 were then cross checked with postcode-specific weather records from the same period.
The likelihood of those exposed to the lowest available sunlight in the first trimester to give birth prematurely was 10 per cent higher than women experiencing the highest levels of sunlight, the team found.
This suggests women may be able to lessen the chances of developing problems with their placenta associated with preterm birth and baby loss by getting outdoors during the first trimester (0 to 13 weeks).
Interestingly, sun exposure in the second trimester (14 to 26 weeks) was not shown to have any impact on premature birth risk.
And the findings were independent of other risk factors such as age and smoking.
In the UK we get most of our vitamin D from sunlight exposure from around late March/early April to the end of September. But getting enough sunlight can be tricky for people living in the UK, known for its grey skies. Pictured, Dean Village, Edinburgh, Scotland
The team is now investigating if artificial light can boost pregnancy health, in order to benefit parents in places with limited sunlight (such as Scotland and other parts of the UK).
Complications caused by preterm birth – defined as babies born alive before 37 weeks of pregnancy – are the leading cause of death in children under five-years-old.
Survivors of preterm birth have higher rates of disability, including learning disabilities and visual and hearing problems, than those born ‘at term’ – born between 37 and 41 weeks.
Previous research from the same group has shown sunnier areas are associated with fewer deaths from Covid-19, and that increased sunlight exposure is linked to lower blood pressure and fewer heart attacks.
This new study has been published in the journal Frontiers in Reproductive Health.
Pregnant women who drink just half a cup of coffee a day are at higher risk of having a small baby, says study
Pregnant women who drink even just a moderate amount of caffeine risk giving birth to a small baby, a 2021 study found.
Expectant women who consumed the caffeine equivalent of as little as half a cup of coffee a day on average had slightly smaller babies than pregnant women who did not consume caffeinated beverages, the US authors said.
Smaller birth size can place infants at higher risk of obesity, heart disease and diabetes later in life.
The experts advise pregnant women to steer clear completely from caffeinated beverages such as coffee, tea and fizzy energy drinks like Red Bull.
The NHS says pregnant women can drink caffeine, but no more than 200 milligrams (mg) per day, which is about the caffeine you’d get in two mugs of instant coffee.
But the team found reductions in size and lean body mass for infants whose mothers consumed below this amount.
Caffeine is believed to cause blood vessels in the uterus and placenta to constrict, which could reduce the blood supply to the foetus and inhibit growth.
It could also potentially disrupt foetal stress hormones, putting infants at risk for rapid weight gain after birth and for later-life obesity, heart disease and diabetes.
Read more: Study links caffeine intake in pregnant women to small baby size