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Abstract
The reduction in the use of neonatal intensive care units (NICUs) during the COVID-19 outbreak has been reported, but whether this phenomenon is widespread across countries is unclear. Using a large-scale inpatient database in Japan, we analysed the intensive neonatal care volume and the number of preterm births for weeks 10–17 vs weeks 2–9 (during and before the outbreak) of 2020 with adjustment for the trends during the same period of 2019. We found statistically significant reductions in the numbers of NICU admissions (adjusted incidence rate ratio (aIRR), 0.76; 95% CI, 0.65 to 0.89) and neonatal resuscitations (aIRR, 0.37; 95% CI, 0.25 to 0.55) during the COVID-19 outbreak. Along with the decrease in the intensive neonatal care volume, preterm births before 34 gestational weeks (aIRR, 0.71) and between 34 0/7 and 36 6/7 gestational weeks (aIRR, 0.85) also showed a significant reduction. Further studies about the mechanism of this phenomenon are warranted.
- neonatology
- health services research
- epidemiology
Data availability statement
Data are available on reasonable request. Due to the contractual restrictions between the authors and the Medical Data Vision, the data are available on request.
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What is already known on this topic?
The decrease in the number of very low birthweight infants and extremely premature births during nationwide lockdowns compared with previous years is reported.
What this study adds?
The total volume of intensive neonatal care (neonatal intensive care unit admission and neonatal resuscitation) showed a significant reduction during the COVID-19 outbreak in Japan.
The numbers of premature births (before 34 gestational weeks and between 34 0/7 and 36 6/7 gestational weeks) also decreased during the COVID-19 outbreak.
Introduction
COVID-19 pandemic has required movement restriction worldwide, leading to changes in lifestyles and physical activities of people, including pregnant women. While there were concerns that perinatal morbidities would increase due to COVID-19 infection itself and maternal psychological stress, early reports from Denmark,1 Ireland2 and the Netherlands3 suggest a drop in very low birthweight infants or in extremely premature births. Anecdotal reports also suggest that the use of neonatal intensive care units (NICUs) have declined during this pandemic in some regions. Nevertheless, whether or not this phenomenon is widespread across countries is inconclusive. Here, we evaluated the nationwide changes in the intensive neonatal care volume, as indicators of neonatal patient acuity, and the number of preterm births during the COVID-19 outbreak in Japan.
Methods
We used a deidentified hospital administrative database, including inpatient setting information from 186 Japanese acute care hospitals that consented to the data utilisation, built by Medical Data Vision (Tokyo, Japan).4 Briefly, this database included deidentified demographic/clinical information and details of provided care collected from Japanese acute care hospitals for per diem reimbursement.
We described weekly trends in neonatal care volume, including the number of caesarean sections, days of NICU admission (=level 3 NICU), days of growing care unit (GCU) admission (=level 2 NICU, providing convalescent care after intensive care) and the number of neonates who needed conventional resuscitations just after birth (hereafter ‘neonatal resuscitations’), during calendar weeks 2–17 of 2019 and 2020 (study period). We also examined the total numbers of preterm births (including live births before 33 6/7 gestational weeks and live births between 34 0/7 and 36 6/7 gestational weeks) on a weekly basis. It should be noted that the number of newborns who died within the first 7 days of life (ie, early neonatal deaths) could not be counted because the other reimbursement system than per diem reimbursement was applied to this category of newborns (as of 2019, the Vital Statistics in Japan showed early neonatal deaths accounted for only 0.7 out of 1000 live births in Japan).5 Due to the data limitation, 147 out of the 186 hospitals were analysed for the trends in preterm births (for the 39 hospitals, birth-related information (ie, dates of birth and gestational age at birth) were unavailable during the study period).
We estimated the changes in the volume of neonatal care and the numbers of preterm births during the COVID-19 outbreak using a ‘difference-in-differences’ model that included a variable for each week, the year indicator (2020 vs 2019) and an interaction variable between the outbreak status (week 10–17, after the adoption of the first governmental policy for COVID-19) and the year indicator. Adjusted incidence rate ratios (aIRRs) were estimated using Poisson regression with Huber-White heteroscedasticity robust standard errors. P value <0.05 was interpreted as statistically significant (Stata 15.1; Stata, College Station, Texas, USA).
Results
Neonatal care
During weeks 2–17 of 2019 and 2020, we observed 6721 caesarean sections from 63 hospitals, 28 474 days of NICU admissions from 22 hospitals, 14 025 days of GCU admissions from 11 hospitals and 692 neonatal resuscitations from 32 hospitals. Three neonatal care aspects showed a significant reduction in weeks 2–9 vs weeks 10–17 of 2020: NICU admissions from 7507 days to 5665 days (aIRR, 0.76; 95% CI, 0.65 to 0.89; p<0.001), GCU admissions from 4269 days to 2651 days (aIRR, 0.71; 95% CI, 0.66 to 0.75; p<0.001) and neonatal resuscitations from 202 to 81 (aIRR, 0.37; 95% CI, 0.25 to 0.55; p<0.001) (figure 1 and table 1). In contrast, the number of caesarean sections showed only a slight decrease (aIRR, 0.91; 95% CI, 0.84 to 0.99; p=0.03), suggesting that the reduced number of births did not markedly influence our findings.
Trends in neonatal care volume and number of preterm births for Japanese acute care hospitals in 2019 and 2020.
Change in neonatal care volume and number of preterm births during weeks 2 through 9 vs weeks 10 through 17 of 2020
Preterm births
During weeks 2–17 of 2019 and 2020, we observed 336 births before 33 6/7 gestational weeks and 804 births between 34 0/7 and 36 6/7 gestational weeks. The number of preterm births showed a statistically significant reduction in weeks 2–9 vs weeks 10–17 of 2020: births before 33 6/7 gestational weeks from 99 to 66 (aIRR, 0.71; 95% CI, 0.50 to 1.00; p=0.05) and births between 34 0/7 and 36 6/7 gestational weeks from 211 to 190 (aIRR, 0.85; 95% CI, 0.74 to 0.98; p=0.02) (figure 1 and table 1).
Discussion
There was a significant decrease in the intensive neonatal care volume across Japanese acute care hospitals during the COVID-19 outbreak. This decline can be attributed to (1) a decline in the number of newborns requiring intensive neonatal care or (2) the limited provision of intensive neonatal care due to the resource allocation and infection control related to the COVID-19 outbreak within hospitals. The decreased neonatal resuscitations, which is essential for depressed newborns, indicated a decline in the rate of birth asphyxia. We also observed significant drops in the number of preterm births (before 34 gestational weeks and between 34–37 gestational weeks). These results at least suggest that the number of high-risk newborns requiring intensive neonatal care was decreased during this outbreak, even though the possibility of the hospitals’ incapability of providing intensive neonatal care remains. Combined with consistent findings in three early reports in Europe,1–3 our study reinforces the hypothesis that changes in lifestyles at the maternal and community levels during the COVID-19 outbreak (movement restriction and the increased focus on infection prevention measures) might have had a positive secondary effect on maternal or fetal conditions, possibly through reduced rates of intrauterine infections or alleviated maternal physical stress. Our findings reappraise the importance of arranging the prenatal living environment to protect newborns and mothers.
Our study has several limitations. First, as is the case for any observational study, we could not fully account for unmeasured confounders. Other factors related to neonatal patient acuity (eg, infectious disease trends unrelated to the COVID-19 outbreak) might partly explain our results. Second, our dataset did not cover all the medical facilities in Japan, and we could not exclude the possibility of patient selection (eg, high-risk pregnancy cases might move from the analytic hospitals). Still, our dataset included as many as 186 hospitals, and the underlying patterns may be similar across Japan. Third, we could not address the trends in stillbirths, another critical indicator of maternal and perinatal conditions, because stillbirths were not recorded in the inpatient database used in this study. Fourth, the mechanisms through which the volume of neonatal care and preterm births reduced during the COVID-19 outbreak remain unknown, and future studies with detailed maternal and neonatal information are warranted.
Data availability statement
Data are available on reasonable request. Due to the contractual restrictions between the authors and the Medical Data Vision, the data are available on request.
Ethics statements
Ethics approval
Ethics Board of the University of Tokyo approved this study (approval no: 2020105NI).
Footnotes
Twitter @AM3824
Contributors AM had full access to the data in the study and takes responsibility for the accuracy and integrity of the data and its analyses. Study concept and design: all authors. Acquisition, analysis or interpretation of data: All authors. Drafting of the manuscript: All authors. Critical revision of the manuscript for important intellectual content: All authors. Statistical analyses: all authors. Administrative, technical or material support: all authors. Study supervision: AM.
Funding Medical Data Vision (Tokyo, Japan) provided the dataset used in this study in the form of labour service.
Competing interests MN is one of the board of directors in Medical Data Vision and received a personal salary from it outside of this study. HN supported Medical Data Vision in algorithm construction and received personal fee outside this study.
Provenance and peer review Not commissioned; internally peer reviewed.