Babies born preterm decreased and stillborn rates remained unchanged during the first four months of COVID-19 lockdowns, according to a study across 26 countries.

Published in Nature Human Behavior, the multidisciplinary study of 52 million births found a 3-4 per cent relative reduction in preterm births – defined as birth before 37 weeks gestation – during the first four months of COVID-19 lockdowns. But the decrease in preterm births was limited to only high-income countries, including Australia.

The International Perinatal Outcomes in the Pandemic (iPOP) Study, one of the largest studies of its kind, involved 167 collaborators across 42 countries with UNSW Sydney co-leading the project alongside The Children’s Research Institute of Manitoba, University of Manitoba, Murdoch Children’s Research Institute and the University of Edinburgh.

“This research represents one of the first large-scale analyses of birth outcomes during the early months of the COVID-19 pandemic,” said study co-lead Scientia Associate Professor Helga Zoega who is an expert in epidemiology and harmonisation of big data for large-scale international collaborations in the School of Population Health at UNSW Medicine & Health.

“Previous research relied on smaller datasets or on populations within a single socioeconomic, regional or cultural group. The scope and breadth of the iPOP dataset allowed us to thoroughly examine global birth trends during the shifting pandemic landscape.”

Read more: One in three IVF cycles undertaken due to male infertility: report

The researchers noted the potential reasons for the decrease in preterm births may include fewer non-COVID infections due to improved hygiene practices and reduced air pollution due to abrupt reductions in traffic during the lockdown period. Infections and air pollution are known to trigger inflammation, which contributes to preterm birth.

“In an average year, there are an estimated 14.8 million preterm births worldwide, meaning that even a modest reduction could have a large impact on global birth trends. We estimate that nearly 50,000 preterm births were averted in the first month of lockdown,” A/Prof. Zoega said.

“Understanding the underlying pathways linking lockdown with the reduction in preterm births could have implications for clinical practice and policy.” 

The iPOP study recorded no difference in stillbirth rates among high-income countries. The stillbirth rate in Australia is about 7.2 per 1000 births, equivalent to about 2000 babies a year.

The iPOP Study is a global partnership

Study co-lead Dr Natalie Rodriguez, Director of Operations, Diversity & Inclusion at the THRiVE Discovery Lab at The Children's Hospital Research Institute of Manitoba and University of Manitoba, said collaborative partnerships forged during the study would continue to strengthen and grow public health research around the globe long after the results were published.

“This is a legacy dataset,” she said. “The scale of data collected during the iPOP study will be used for future research projects for years to come.”

Study co-founder Dr Meghan Azad, from the University of Manitoba, said the study was developed at an astonishing speed, particularly given the scope of the collaborative partnerships.

“The iPOP study united and mobilised public health researchers in a truly unprecedented way,” she said. “This level of collaboration was grounded in a unified sense of purpose that couldn’t have happened at another period in history. Everyone was eager to do their part to support mothers and babies during a global health crisis.”

Read more: Private obstetric care increases the chance of caesarean birth, regardless of health needs and wishes

To encourage actionable policy and practice recommendations, the iPOP consortium worked closely with partners including the World Health Organization (WHO), the United Nations Population Fund, World Vision and the Public Health Agency of Canada.

A/Prof. Zoega said it was an “incredible partnership between 167 collaborators across 42 different countries”.

“Everyone was eager to contribute expertise and data to better understand how this global health crisis affected mothers and babies.

“As a population health researcher, it was highly motivating to see so many high-quality datasets come together and to work on harmonising them across countries and analytical approaches."

The next step includes research into causal pathways to better understand the reasons behind our findings, that is what are the underlying reasons for reductions in preterm birth during lockdowns, according to A/Prof. Zoega.

“There is already ongoing research into this on a systematic and individual level, including the role of reductions in non-SARS-CoV-2 infections, reduced air pollution and changing stress levels among pregnant people during periods of lockdown.”

The study was supported by the International COVID-19 Data Alliance (ICODA), an initiative funded by the Bill and Melinda Gates Foundation and Minderoo as part of the COVID-19 Therapeutics Accelerator and convened by Health Data Research (HDR) UK, in addition to support from the HDR UK BREATHE Hub.