Lockdown Sees Fall in Rate of Premature Birthby Laura Driver
A drop in air pollution, reduced exposure to infections and lower levels of work-related stress have been suggested as the reasons for an “unprecedented” fall in the number of babies being born prematurely during lockdown, two separate studies have shown.
Researchers in Ireland and Denmark took advantage of the “natural experiment” of lockdown to look at its impact on rates of pre-term birth. The studies, neither of which have yet been published in peer-reviewed journals, both showed large falls in the numbers of babies born premature.
The Irish study looked at the number of babies born weighing less than 3.3 pounds – a good proxy for pre-term birth – in the Limerick, Clare and North Tipperary region of the country between January and April this year.
They found that the number of very low birth weight babies delivered during this period fell by nearly three quarters during lockdown compared to the average. For every 1,000 babies born during the period studied 2.17 were premature, researchers found.
The average rate for the region is nearly four times higher: 8.18 low birthweight babies are born for every 1,000 births.
Professor Roy Philip, consultant neonatologist and paediatrician at University Hospital Limerick and lead author of the study, was on holiday when lockdown began and on his return he noticed that there had been no orders for the breast-milk based fortifier used to feed the tiniest babies. Staff told him they had not ordered any because none of these babies had been born.
“There are normal fluctuations in the numbers of babies born but when they told me that none had been born for that length of time I thought that was unusual. And that triggered us to dive deeper into the data,” he said.
He was so surprised at the findings that he thought he had made a mistake. “I thought I wasn’t reading or calculating it correctly – I triple-checked the data to make sure it was correct,” he said.
The team from Limerick only knew about the Danish study when it was published but Prof Philip said the results were a “mirror image” of their own.
The Danish study looked at the number of babies born in Denmark before 28 weeks gestation between March 12, the day lockdown began, and April 14 this year and then compared this to the numbers born during the same period in the previous five years.
Some 58 very premature babies were born during the entire period but the rate was 90 per lower during lockdown, researchers found. The pre-term birth rate was 0.19 for every 1,000 live births this year, compared to an average of 2.19 per 1,000 during the preceding years, the researchers found.
The reasons for premature birth are still poorly understood and both the Irish and Danish researchers hope that “nature’s experiment” could provide vital information. They point to a number of factors including a reduction in air pollution, less work-related stress and lower exposure to infections during pregnancy.
Prof Philip said it was hard to pinpoint the exact reason for the drop in premature birth rates in either study. “We have never had an opportunity in the recent past to control a population for all these social and environmental factors and behaviour aspects that lockdown brought. We think it’s a cumulative effect,” he said.
Prof Philip said the findings may indicate that it would be better for women to take maternity leave earlier in the pregnancy, rather than just before the birth.
However, he said more international data was needed. He added: “Our findings may not be exactly replicated in every region or country of the world. But what our study does point to is looking at the family-centred aspect of antenatal and pre-natal care.”
However, Andrew Shennan, professor of obstetrics at King's College, London, said other factors could be at play. He pointed to data published in the Journal of the American Medical Association from St George's Hospital in London that showed an increase in stillbirths during the pandemic, mainly associated with women not coming to hospitals for antenatal visits.
"Women are not being monitored. If I pick up a baby who is compromised I deliver them early - and that's one of the causes of pre-term birth. Around a third of pre-term births take place because we decide to deliver them early," he said.
"If there was a pollution effect or an environmental effect it might make a difference but to cause an 80 to 90 per cent reduction is to me completely implausible," he said.