TORONTO -- Ontario’s strict lockdown measures during the first six months of the COVID-19 pandemic are associated with fewer premature births before 32 weeks gestation than in years prior, according to a new study.

The findings, published in the JAMA Network Open journal on Wednesday, suggest that public health restrictions to curb the spread of the coronavirus may have reduced the risk of very early delivery when compared to the previous five years.

For the study, researchers from Unity Health Toronto, a health network comprised of Providence Healthcare, St. Joseph’s Health Centre, and St. Michael’s Hospital, compared data provided by ICES on the 67,747 births that occurred in Ontario hospitals between March 15, 2020 and Sept. 30, 2020 to births during the same period in the last five years.

While the team was unable to study out-of-hospital births, those only account for less than three per cent of all births in the province. They also said they were unable to evaluate other possible risk factors for preterm birth, such as smoking.

Additionally, they did not evaluate the risk of preterm birth among people who had contracted COVID-19 during pregnancy because there was only a small number of them, the study stated.

Based on the data, the researchers found there was no overall reduction in preterm births before 37 weeks of pregnancy, but there was a slight decrease in very early deliveries before 32 weeks. They concluded that early lockdown measures in Ontario may have been associated with a reduced risk of very early preterm birth.

“Preterm birth is a leading cause of adverse childhood and long-term outcomes,” Dr. Andrea Simpson, an obstetrician-gynecologist at St. Michael’s Hospital in Toronto, said in a release.

“If lockdown measures do reduce the risk of preterm birth, it may lead to novel areas of research to understand how we can further improve pregnancy and perinatal outcomes.”

The findings are in line with similar studies conducted in Denmark and Ireland where comparable strict lockdown measures were in effect, the study noted. In contrast, the researchers said there was no difference in preterm births in a population-based study in Sweden where there wasn’t strict lockdown measures early on in the pandemic.

The study also compared the number of stillborn deaths in Ontario during the first six months of the pandemic to those in the same period during the previous five years, but they found there was no difference in overall risk.

The researchers said the risk for other perinatal outcomes, such as low birth weight, neonatal intensive care unit admission, and early or late neonatal death, during those first six months of lockdown also didn’t increase. Researchers called that “reassuring” because it suggests pregnant people were still continuing to access the care they needed despite the restrictions.

“Obstetrical care changed quickly in response to the COVID-19 pandemic, including the introduction of virtual care. We are looking at other changes in obstetrical care during the pandemic and the effect on patient outcomes,” Simpson said.

“This research is important during the subsequent waves of the pandemic and after to determine whether these changes in care have resulted in different outcomes for patients.”