Introduction

The global COVID-19 pandemic has been stressful for expectant families and their health care providers.  On the clinical side, so much is still unknown about transmission of the coronavirus from pregnant person to fetus, or parent to newborn, or even via human milk.  Pregnant people have been trying to isolate as much as possible whenever and wherever possible, but social circumstances, economic concerns and a whole host of other issues make it nearly impossible for many, many families.

The emotional impact of being pregnant and birthing during the COVID-19 pandemic is also not inconsequential.  Isolation, loneliness, fear, stress and worry have forced many people to go through their pregnancies and birth their babies without the social support of friends, family and doulas.  This has added a whole other layer of complications that were not expected.

But could there be a glimmer of a silver lining amongst all this concern?  First reported from physicians in Ireland and Denmark, with an upwelling of more anecdotal reports from other countries, it appears that the number of babies who are born prematurely, (and most noticeably, very prematurely) has been significantly reduced.  In the study that has yet to be peer-reviewed and is still in preprint, “Changes in premature birth rates during the Danish nationwide COVID-19 lockdown: a nationwide register-based prevalence proportion study” found that there were significantly less babies born prematurely during the COVID-19 lockdown than in the previous five years.

How was the study done

Through the use of data collected as part of the comprehensive national Danish newborn screening system, blood samples and corresponding birth data including gestational age is aggregated through a unified collection program.  Each sample is processed within three days of collection, so there is practically zero lag time between birth and birth information being captured.  Data were collected from singleton births during the lockdown period of March 12-April 14, 2020 and the corresponding same periods in the preceding five years.  Information was also gathered for the period before the lockdown, January 20- February 22, 2020 as well as the same period in the preceding five years.  The period of pre-lockdown births was also compared in 2020 with the previous five years in order to examine a time period not influenced by the lockdown.  Only singleton births were included.

Babies were classified as extremely premature if they were born before 28 whole weeks, very premature if they were born between 28 and 31 whole weeks, moderate/late premature if gestational age was 23-36 weeks, term if they were born 37-42 weeks and late term if the baby was born after 42 weeks.

What were the results

31,180 live singleton births in total occurred in the period of March 12 to April 14 for the years 2015-2020.  The number of births in each year were similar, including during the lockdown period.  There was a total of 1566 premature births (gestational age before 37 weeks) during those years. Analyses demonstrated that the distribution of gestational age at birth in 2020 differed highly significantly from 2015-2019.  Additionally, the number of extremely (<28 weeks) and very premature (<32 weeks) was significantly different in 2020 than in the periods of 2015-2019.

32,070 births occurred in the period January 20- February 22, in the years 2015-2020, which was the “control group.”

Table 1: Gestational age categories and the distribution of singleton births throughout the study periods. (March 12, - April 14, (2015 – 2020)).

Table 2: The distribution of births permille, by gestation age category for the lockdown period (March 12 – April 14, 2020) compared with consolidated data from March 12 – April 14, 2015-2019.

According to the researchers:

“It is evident that the reduction in proportion of extremely premature births was not present in the months immediately prior to the lockdown…and a significant shift in gestational age at birth among extremely and very premature births during the lockdown period, this shift is not noted in later weeks."

Discussion

Prematurity is the leading cause of death amongst children under the age of 5.  Any reduction in premature births, will reduce the mortality rate amongst children under the age of 5.  In addition to the reduced mortality rate, a reduction in the morbidity rate amongst children born prematurely will also provide long term benefits.  In some cases, the reason for premature birth are understood, but for the majority of premature births, it is difficult to identify a reason.  During the period of lockdown, reduced air pollution, less contact with other individuals, increased hygiene and a different work environment were all present.  The researchers believe that all these factors influenced the prematurity rate.

Systemic maternal infection is known to cause premature births.  The conditions (more hygiene, less contact) under which pregnant people quarantined may have reduced this infection rate.  The potential also exists that a correlation in the reduction in physical work that people were doing may also have played a role.  Air pollution decreases also may contribute to the prematurity rate, as it is documented that air pollution levels may contribute to 18% of the premature births worldwide.

Conclusion

While the paper has yet to be peer reviewed or published, the researchers conclude:

“Our data indicates that the occurrence of extreme prematurity may be further reduced through preventive measures. If this tendency is confirmed, future studies may even identify causal mechanisms that may be applicable outside a lockdown. Possibly, lessons learned during the COVID-19 pandemic and lockdown may contribute to improved guidelines leading to fewer extremely premature births and thus decrease infant morbidity and mortality.”

Resources

Hedermann, G., Hedley, P. L., Baekvad-Hansen, M., Hjalgrim, H., Rostgaard, K., Poorisrisak, P., ... & Lausten-Thomsen, U. (2020). Changes in premature birth rates during the Danish nationwide COVID-19 lockdown: a nationwide register-based prevalence proportion study. medRxiv.

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