MRC/CSO Social and Public Health Sciences Unit

Published 19th May 2022

By Moritz Oberndorfer, Postgraduate researcher, Center for Public Health, Medical University of Vienna and visiting researcher at the MRC/CSO Social and Public Health Sciences Unit.

Babies conceived during the COVID-19 pandemic and their mothers are likely to be, on average, healthier than babies conceived before and after the pandemic. Yes, this sounds a bit crazy – how could this global crisis have improved anyone’s health? Well, it didn’t. The LoCo (Lockdown Cohort)-effect tries to explain why population health research may nonetheless make this counterintuitive observation soon.

Who is the Lockdown Cohort (LoCo)?

First, we need to clarify which babies are LoCo and which aren’t. The LoCo begins with the first strict lockdown measures enacted in response to the COVID-19 pandemic plus the average gestation time – about nine months. In most European countries, lockdowns were in place by late March 2020 which means, in Europe, the LoCo-effect is not expected to be seen before November/December 2020.

To simplify, the most important difference between the LoCo and any other birth cohorts is that the LoCo is conceived during the COVID-19 pandemic. But how can this seemingly minor difference in time of conception result into the substantial and counterintuitive effect on health we are suggesting?

The disruptions to health services, economy, and social life during the COVID-19 pandemic may have created barriers to starting or enlarging families. This might be, for example, due to changed access to relevant services or increased uncertainty about future income and employment. Now, the key force behind the LoCo-effect is the extent of inequalities that existed before the pandemic and their amplification during the pandemic.

It became clear within the first months of the COVID-19 pandemic, that like the pandemics that came before, disadvantaged groups were disproportionately carrying the economic and health-related burden. This robust evidence has led us to expect that any newly created barriers to having a baby were also unequally high. In other words, the pandemic may have made it more difficult to realise plans for having a baby among disadvantaged families than advantaged families compared to before the pandemic. Thus, the LoCo may consist of less babies born to disadvantaged families and/or more babies born to advantaged families. It is therefore possible the LoCo will, on average, start life in more advantaged circumstances than babies conceived before and after the COVID-19 pandemic (if no other storm has come by then).

The data so far

While it is too soon to fully investigate the strength of the LoCo-effect, Scotland’s leading data infrastructure has allowed us to get a first glance at how the pandemic changed the number of births among more and less disadvantaged areas of Scotland. We analysed the monthly number of births in Scotland up to November 2021 – about a year into the LoCo. Although we expected to see sudden changes in the number of births occurring 9 to 10 months after the first lockdown started in March 2020, my eyes widened when I ran the code that would show me the answer.

Starting with November 2020, the number of babies born in the most disadvantaged 20% of Scotland’s areas was considerably below the number we would have expected based on the number of births outside the LoCo. This gap reached its peak in February 2021 when 727 instead of the expected 942 babies were born in the 20% most disadvantages areas in Scotland. That is more than 20% fewer babies than usually born in February in these areas. If we add up these differences between what we would have expected and what we actually observed for each month of the LoCo, we see that between November 2020 and November 2021 there were about 10% fewer births than expected in the most disadvantaged areas.

To put it differently, within just a year more than an entire pre-pandemic month of babies has not been born among these areas. This astonishing decline wasn’t only visible amongst the most disadvantaged areas, but also in the second and third most disadvantaged fifths, albeit to a lesser extent. In contrast, in the 40% least disadvantaged areas of Scotland the number of births barely changed.

More questions than we can answer – for now

So, the LoCo-effect does not imply that the COVID-19 pandemic has actively improved health for any pregnant women or babies. Yet, from what we’ve seen so far, the pandemic has significantly changed who was able to have a baby and who wasn’t. This change was likely driven by factors that are also well-known to affect offspring’s health; not just in infancy but throughout their entire lives. This combination of sudden changes in average parental characteristics and their known influence on offspring’s health may produce a birth cohort that is unexpectedly healthy despite born during a global crisis. This counterintuitive possibility is the essence of the LoCo-effect. Importantly, the LoCo-effect reflects the extent of socioeconomic inequalities in women’s circumstances before and during the pandemic and therefore underlines the need to reduce inequalities in this population.

At this moment, the outlined LoCo-effect opens more questions than we can answer. For example, it is possible that the LoCo-effect will be overshadowed by the adverse effects this pandemic may have had on the health and well-being of pregnant women and their babies. Crucially, while it looks like the gap between expected and observed births in disadvantaged areas shrunk as lockdown measures were eased between pandemic waves, we don’t know whether the babies missing in the LoCo remain missing or will be born eventually. Although recent research suggests that the LoCo-effect transpires in other countries as well, we expect this to be in varying strength as the LoCo-effect depends on the extent of socioeconomic inequalities in a population and the lockdown measures it was exposed to.

In any case, research on the LoCo-effect has only just begun and I’m looking forward to what it will teach us about population health and health inequalities.

 

---

First published: 19 May 2022