Although pregnant women have been warned of their potential for more serious COVID-19 disease, several early reports suggest one positive finding for this population – that pandemic lockout constraints may have coincided with a reduction in preterm birth.
Early studies noted a drop in the premature birth rate during the lockout, highlighting the potential “silver lining” of the pandemic. But while these findings are encouraging, experts say there is still not enough data to know whether the reduction in preterm birth was widespread or what factors could have led to a decline in this outcome at all.
“The jury came out, in terms of overall impact [of the pandemic] on preterm birth, “said Rahul Gupta, MD, health minister, chief medical and health officer in March of Dimes. Although early data may provide some insight into lifestyle changes such as working from home and remote access to health care, Gupta said said more information was needed before conclusions could be drawn on reducing preterm birth – and on which populations were most affected.
According to the WHO, premature birth is the leading cause of death in children under 5 years of age. In the US, the birth rate gave birth prematurely in a steady upward trajectory, and 2019 is the fifth consecutive year that has risen. Between 2018 and 2019, the premature birth rate increased by 2%, according to the CDC.
Clinicians in Denmark and Ireland first noticed a drop in preterm births last spring – especially the earliest and most critical ones. A Danish preprint study, which included more than 31,000 newborns born between 2015 and 2020, showed about a 90% reduction in extremely premature births (those born before the 32nd week of pregnancy) during the lock-in period. In Ireland, another study published in BMJ Global Health recorded a 73% decrease in births with extremely low birth weight, from January to April last year.
Other studies have found that rates are declining for certain populations. Recent systematic review and meta – analysis in Lancet Global Health found that while the overall premature birth rate did not differ significantly before and during the pandemic, the rate in high-income countries fell by 9%. Spontaneous preterm births in high-income countries recorded an even larger decline, falling by almost 20%.
“Interestingly, there are lucky numbers mostly from high-income countries,” said the study’s lead author, Asma Khalil, Ph.D. Med., From the University Hospitals of St. George’s NHS Foundation Trust of London.
Some reports from the U.S. also reflected a decline, albeit a smaller one. Last April, Stephen Patrick, MD, MPH, of Vanderbilt University, wrote on Twitter that he noticed a smaller number of newborns in the Neonatal Intensive Care Unit (NICU) at his facility.
Last month, Patrick and colleagues published a study in JAMA Pediatrics shows the link between preterm births and home stay orders in Tennessee. Patrick’s team found that the risk of preterm birth dropped by almost 15% during the lock-up period, after determining the mother’s age, race, level of education, hypertension and diabetes.
Naima Joseph, MD, MPH, an associate of maternal and fetal medicine at Emory University School of Medicine, said the decline could be linked to changes in the environment and lifestyle that occurred in the first months of the pandemic.
Alison Gemmill, a doctor from Johns Hopkins University, said that numerous changes during the lock could be related to the fall in the birth rate. When most cars veered off the road, there may have been a drop in the number of premature births associated with air pollution. In addition, as pregnant women switched to telecommuting and found themselves at home and on their feet, Gemmill said there may have been a drop in physical stress.
The second hypothesis, Gemmill added, was that a decrease in preterm births could occur at the same time as an increase in stillbirths. Some reports show an increase in stillbirths during the pandemic (including Khalil’s analysis), but U.S. data has not yet confirmed this increase.
Gemmill and colleagues published a study last week (which has not yet been reviewed) that shows that the premature birth rate in the U.S. is one of several birth outcomes that was lower than expected in March and April last year. But the group also noted that the rate fell again in November and December – coinciding with the months when the rate of infection rose.
“Something is definitely going on,” Gemmill said in an interview. She added that the rates observed by her group are crude and do not describe how this has affected different demographic groups in the US. However, she said her research “reveals a really important signal that doesn’t occur in birth outcome research”.
Not all US data confirmed this pattern. A JAMA a study on nearly 9,000 newborns at the University of Pennsylvania found that mothers in 2020 had the same risk of preterm birth as they had years earlier.
Gupta from March Dimes stated that the United States is not a homogeneous society and that the birth rate will look different in different populations. For example, black parents are 50% more likely to have a premature baby than white or Hispanic parents. And while preterm births could have coincided with telework, this would not apply to basic workers who continued to work during the lockdown.
As for the outcomes of preterm births during a pandemic, Gupta said that after scientists break down the data according to demographics, social determinants of health and medical comorbidities, he expects “different outcomes” to occur. There is no national real-time birth control data in the U.S. – so it will take time for these outcomes to be fully understood.
As for theories about what factors may have influenced premature birth, Joseph said that “these data generally led to the creation of more hypotheses than to anything else that is more decisive.”
Gupta agreed, adding that more research should be done on both the effects of COVID-19 infection and the indirect effects of the pandemic.
“I think we really need to better understand what factors during COVID – including locking, unemployment, social interactions, mental health, drug adherence, job loss – all played a role,” he said. “I don’t think any of these factors should be taken for granted.”