Thousands of pre-term births may have been prevented by Covid vaccines, a new study suggests.
Despite widespread misinformation about the vaccines causing fertility issues, researchers in California linked the shots to a 78 percent decrease in preterm births among mothers-to-be who were infected with the virus.
They analyzed data on millions of births recorded in the state between 2014 and 2022 and detected a spike in pre-term births in 2020 — when the virus was first spreading in the US.
The study attributed this to Covid infections in pregnant women, which raise the risk of a pre-term birth because of inflammation and stress from an infection.
But by 2022 the preterm birth rate had dropped back to pre-pandemic levels — following the roll out of Moderna and Pfizer’s vaccines.
Thousands of pre-term births may have been prevented by Covid vaccines, a new study suggests (stock image)
It’s thought that the jabs primed mother’s immune systems to recognize and attack the virus early in an infection, slashing the risk of severe disease.
Mothers-to-be who were infected with Covid had an at least 60 percent higher risk of a preterm birth — or giving birth to a child before 37 weeks gestation — in the early stages of the pandemic compared to those who were not infected, studies suggest.
Mothers-to-be are more vulnerable to severe infections because their immune systems are weaker during pregnancy.
Scientists suggest Covid also raised the risk of a preterm birth because it could trigger a ‘cytokine storm’.
This is an over-reaction of the immune system which sees the body attack healthy tissue.
About one in ten children in the US are born early — or before 37 weeks gestation — surveys suggest.
In many cases, youngsters do not suffer ill effects. But those born early are at a higher risk of complications including infections, asthma and developmental delays.
Researchers analyzed data from California because the state had recorded on birth certificates whether expectant mothers had been infected with Covid since June 2020.
Mothers were tested for the virus before they were admitted to one of the state’s 400 hospitals or birthing centers where possible.
There are 400,000 births in California every year on average, equivalent to many countries — and allowing results to be generalized worldwide.
Results showed that the risk of a pre-term birth for a mother rose 78 percent for those infected with Covid in the year 2020 (or rose from 6.9 to 12.3 percent of all births being pre-term).
The rate rose shifted again by 4.1 percent in 2021 with the emergence of the more severe Delta variant.
But had dropped back to pre-pandemic levels by 2022, following the major roll out of the vaccine, mounting infections and the emergence of the milder Omicron variant.
In areas where vaccine uptake was higher, scientists found that pre-term births in Covid infected mothers dropped a year earlier than in those areas with low uptake.
California started rolling out the Covid vaccine on December 14, 2020, and in July 2021 also started dishing out the shots to pregnant women.
By December 2022, 84 percent of California’s residents had got at least one dose of the vaccine.
Jenna Nobles, a sociologist at the University of Wisconsin-Madison who led the research, said: ‘In ZIP codes with the highest vaccination rates, the excess risk of preterm birth declines much faster.
‘By the summer of 2021, having Covid in pregnancy had no effect on preterm birth risk in these communities.
‘It takes almost a year longer for that to happen in the ZIP codes with the lowest vaccine uptake.
‘That highlights how protective Covid vaccines have been. By increasing immunity faster, early vaccination uptake likely prevented thousands of preterm births in the US.’
Vaccines triggered immunity against the virus by priming the immune system to fight off the infection to avoid severe disease.
But infections early in the pandemic likely also helped, scientists said, because these also taught younger women’s immune systems how to fight the virus off.