Public Health Agency of Sweden's Brief Report: Pregnant and postpartum women with severe acute respiratory syndrome coronavirus 2 infection in intensive care in Sweden

Abstract The Public Health Agency of Sweden has analyzed how many pregnant and postpartum women with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection have been treated in intensive care units (ICU) in Sweden between 19 March and 20 April 2020 compared with non‐pregnant women of similar age. Cases were identified in a special reporting module within the Swedish Intensive Care Registry (SIR). Fifty‐three women aged 20‐45 years with SARS‐CoV‐2 were reported in SIR, and 13 of these women were either pregnant or postpartum (<1 week). The results indicate that the risk of being admitted to ICU may be higher in pregnant and postpartum women with laboratory‐confirmed SARS‐CoV‐2 in Sweden, compared with non‐pregnant women of similar age.


| INTRODUC TI ON
In the beginning of April 2020, the Public Health Agency of Sweden (PHAS) noted that a relatively high number of pregnant and postpartum women with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were or had been treated in intensive care units (ICU) in Sweden. When analyzing the published literature on pregnancy and SARS-CoV-2, gaps in knowledge were identified, especially whether being pregnant represents a risk for increased susceptibility to infection, severity of clinical presentation and adverse outcomes for mothers and neonates. [1][2][3][4][5][6][7] Through dialogue with corresponding authorities in other European countries and the USA it became apparent that none had seen a comparatively increased number of pregnant or postpartum women with SARS-CoV-2 infection requiring intensive care.
As a first step, PHAS analyzed how many pregnant women with SARS-CoV-2 infection had been treated in ICU in Sweden, compared with non-pregnant women of similar age. This analysis was shared and discussed with the National Board of Health and Welfare and with professional medical organizations in Sweden. This is a rapid assessment of the current situation in March and April. Further analyses and research will hopefully shed more light on pregnancy and coronavirus disease 2019 (COVID-19).

| MATERIAL AND ME THODS
The Swedish Intensive Care Registry (SIR) 8  For some pregnant/postpartum women, the main reason for intensive care was not symptoms of SARS-CoV-2 infection, but other conditions. It was not possible to ascertain whether SARS-CoV-2 was the primary reason for intensive care for the non-pregnant women. Therefore, a decision was made to include the entire age group, regardless of whether SARS-CoV-2 was the main reason for intensive care admission, as long as the patient had laboratory-confirmed SARS-CoV-2.
Population data were obtained from the Swedish population registry. 9   Three sensitivity analyses were also performed. As the estimate described above only includes pregnancies from gestational age 27 weeks, there is a degree of under-ascertainment regarding the number of pregnancies, because miscarriages and early stillbirths are not included. To compensate for this, a 50% higher value for the number of pregnancies was used in the first sensitivity analysis, based on a miscarriage rate of 28% (ranging from 10% at 20 years of age to 40% above 35 years of age), 10 to be sure to be well above this rate. This may be an unrealistically high number of pregnancies, but it was adopted to avoid an overestimation of risk while interpreting the results.
In the second sensitivity analysis, the number of women requiring ICU was reduced to contain only those who received invasive mechanical ventilation, to account for the possibility of a slightly lower threshold for admitting pregnant women to ICU as a precaution. The third sensitivity analysis combined the aspects of the first and second sensitivity analyses.

| Ethical approval
This study was completed as part of PHAS responsibility for public health issues at a national level and its subsequent work on surveillance of COVID-19 during the pandemic and was exempt from formal ethical approval.

| RE SULTS
In total, 53 women aged 20-45 years with SARS-CoV-2 admitted in ICU were reported during the period between 19 March and 20 April. Thirteen of these women were pregnant (n = 11) or had recently given birth (n = 2) on admission (within 1 week postpartum).
Their age varied between 20 and 35 years, and gestational age var-

Key message
The risk of requiring intensive care may be higher in pregnant women infected with SARS-COV-2, or women who have recently given birth, compared with non-pregnant women of similar age. presented in Table 1. Relative risk indicates the increased probability of receiving intensive care in conjunction with laboratory-confirmed SARS-CoV-2 for pregnant or postpartum women, compared with non-pregnant women in the same age group.

| D ISCUSS I ON
We identified that the risk of requiring intensive care may be higher in pregnant/postpartum women with laboratory-confirmed SARS-CoV-2, compared with non-pregnant women in the same age group, even after accounting for miscarriages and early stillbirths (<27 weeks) in the denominator. This risk was higher than that calcu- Information on pregnant women receiving intensive care in Sweden with COVID-19 will be continuously monitored and more refined analyses will be performed. Moreover, a joint research project has been initiated to elucidate the impact of COVID-19 during pregnancy on maternal and neonatal outcomes, using data from the Swedish Pregnancy Register, 12 the Swedish Neonatal Quality Register, and SmiNet. 13

| CON CLUS ION
The risk of requiring intensive care may be higher in pregnant women precautions. This study needs to be replicated in other countries and more detailed information on symptoms, treatment, and outcomes for pregnant and postpartum women managed in ICU is needed.

ACK N OWLED G M ENTS
This brief report has been possible due to joint efforts of several colleagues at the Public Health Agency of Sweden and colleagues at the regional communicable disease control units, in collaboration with other partners, such as professional medical associations and SIR.  2 Only cases requiring invasive mechanical ventilation. 3 Sensitivity analyses 1 and 2 combined.