Page 77 - IJPS-10-3

International Journal of
Population Studies COVID-19 and fertility in Costa Rica

newborns and their parents. Using the mother’s cédula, before the pandemic and delivered during the first 9 months
each birth record can be linked to the mother’s birth record of the pandemic, from March to November 2020; (iii)
in the same data set to obtain two key data: the mother’s pandemic, which included births that were likely conceived
age and birth order. It also provided a complete birth during the first 12 months of the pandemic and delivered
history of every woman. Linking the mothers’ records in 2021 (December 2020 was an unclassifiable transitional
to the electoral roll database (padrón electoral) can help month); and (iv) late-pandemic, which included births
unveil their potential communities (distritos) of residence. conceived in the second (and essentially final) year of the
The distrito is the smallest administrative unit in Costa pandemic and delivered in 2022.
Rica; there are close to 500 distritos, each with an average Four characteristics of mothers were analyzed as effect
population of approximately 10,000 people. modifiers: (i) Native or immigrant status; (ii) age, which
The birth histories were complemented with was categorized into two groups with a cutoff at 25; (iii)
information on a censoring date for women who died parity (nulliparous women having their first births, one-
or disappeared from the voting rolls (they probably child mothers having their second births, and mothers
emigrated). This information was obtained by linking this of two or more children); and (iv) socioeconomic status
database with those of death registries and the 2018 and (SES) of the community as measured by the proportion
2022 voting rolls using the cédula number. The data file was of adults with a high school diploma in the mother’s
then organized as a “survival-time” data set with multiple home distrito according to the 2011 census, which was
exit events (births) using the Stata software (StataCorp, categorized into three groups of approximately similar size
2020). Monthly counts of births and exposure (woman or terciles: low if <28%, medium if 28% to 42%, and high if
months) were aggregated into a data file covering the period 43% or above. The 2011 census data concerning SES were
from January 2015 to December 2022. Fertility rates were utilized in this analysis under the assumption that there
computed as the ratio of births to exposure multiplied by were no SES tercile changes in the surveyed communities
12,000. The aggregate data are presented in Supplementary over the nine years between 2011 and the pandemic. This
File. Access to the micro-databases was granted by the TSE was validated through a comparison between the 2000 and
after signing an inter-institutional agreement. Since non- 2011 census data depicting a very minor shift in the SES
native mothers have neither a cédula nor a birth record, it tercile occurring in only 4 out of 472 distrito.
is not possible to obtain exposure and fertility rates using The discussion section includes a sensitivity analysis
their birth information recorded in the database; therefore, of the choice of an alternate econometric method adapted
the fertility rates of non-native mothers were not included from the “interrupted time series” method (McDowall
in the analysis. et al., 1980). Pre-pandemic trends in the monthly general
We amassed a total of 235,000 valid birth records and fertility rate (GFR) were estimated using Poisson regression
789,000 valid records of native-born women aged 15 – models for the period between 2015 and November
49 years registered during the period between 2018 and 2020. These trends were then treated as counterfactual
2022. It has previously been established that the registration (expected fertility in the absence of the pandemic) to
coverage of birth is 100% in Costa Rica (Pérez-Brignoli & identify its potential impact of the pandemic on fertility.
López-Ruiz 2017). The outcome variables of interest were For presentation purposes, the monthly fertility rates were
year-on-year variations in birth counts and fertility rates, first adjusted for seasonal fluctuations, as had been done by
similar to those measured in Sobotka et al.,’s study (2021). Bailey et al. (2023).
Rates, or counts, during a period, were compared to those
from an equivalent period 12 months earlier to compute 3. Results
annual variations that are free of seasonal variations. For 3.1. Drops in fertility and birth counts of
example, the change in the fertility rate of January 2021 was native-born and immigrant women
determined by comparing it to the rate in January 2020, or The TFR for the native-born Costa Rican population
the change in the fourth quarter of 2021 was computed by reached a very low level of 1.22 births per woman in 2020
comparing its rate to that in October to December 2020. (Table 1), falling below the so-called threshold of “lowest-

The month of delivery relative to the pandemic timeline low fertility” of 1.3 births (Kohler et al., 2002). Considering
was treated as another outcome variable of interest. Births that the gestation of newborn babies usually takes
were categorized as occurring in four distinct periods: (i) 9 months, it is our deduction that almost all births in 2020,
Pre-pandemic, which included births in the year before analyzed in this study, were conceived before the pandemic
March 2020, the month when the pandemic began; (ii) onset, which in Costa Rica occurred in late March 2020.
quasi-pandemic, which included births likely conceived In 2021, the TFR of native women fell to 1.14 births,

Volume 10 Issue 3 (2024) 71 https://doi.org/10.36922/ijps.1310