Abstract
Objectives:
To describe the prevalence of overall and asymptomatic SARS-CoV-2 infection in pregnant women admitted for delivery at 3 maternity units in North Wales.
Design:
A prospective multicentre cohort study of universal testing for SARS-CoV-2 infection offered to all pregnant women admitted for delivery.
Setting:
475 women admitted for delivery in 3 maternity units in North Wales at Bangor, Bodelwyddan and Wrexham between 3rd June and 2nd July 2020.
Methods:
Testing performed by reverse transcription-polymerase chain reaction of nasopharyngeal swabs with concurrent universal screening for signs and symptoms of COVID-19 infection.
Results:
The overall prevalence of SARS-CoV-2 infection in pregnant women in North Wales was 2.74% with an asymptomatic prevalence of 1.89%. 69% of women positive for SARS-CoV-2 at delivery were asymptomatic.
Conclusions:
Pregnant women with SARS-CoV-2 infection are not reliably identified using symptom and temperature screening as most infected women are asymptomatic on admission. The prevalence of maternal infection and asymptomatic carrier rates vary based on geographic differences in disease prevalence. It is suggested that a trial period of universal testing may help determine whether such an approach is appropriate for an individual maternity unit.
Introduction
The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that causes coronavirus disease 2019 (COVID-19), was first reported in Wuhan, Hubei province, China in December 20191. The World Health Organization labelled the novel coronavirus outbreak a pandemic on 11th March 2020 and North Wales reported its first COVID-19 related admission on 12th March 2020. The first pregnant woman with COVID-19 was admitted on 16th March 2020 in Bangor.
Pregnant women do not appear more likely to contract the infection than the general population2. However, pregnancy itself alters the body’s immune system and response to viral infections which can cause more severe symptoms3. Pregnant women are therefore included in the clinically vulnerable patient group who have been advised to practice social distancing and avoid anyone who has symptoms suggestive of coronavirus. Pregnant women present a unique challenge as they require multiple interactions with health professionals, and most will eventually be admitted to hospital for delivery. Maternity services provide essential and time critical care that must be maintained during the pandemic. Robust infection control measures have been implemented to reduce the spread of infection in maternity units.
The mean incubation period for SARS-CoV-2 is 5 days4and viral shedding may begin 2-3 days before the appearance of the first symptoms5. Asymptomatic carriers of the virus therefore contribute to the spread of the disease. Screening for asymptomatic infection is suggested to protect pregnant women, their babies and healthcare workers6.
Objectives:
This study aims to describe the prevalence of overall and asymptomatic SARS-CoV-2 infection in pregnant women admitted to hospital for delivery at 3 maternity units in North Wales. These units are at 3 acute hospitals (Ysbyty Gwynedd in Bangor, Glan Clwyd Hospital in Bodelwyddan and Wrexham Maelor Hospital). We also characterise the clinical course of those who had a positive result.
Methods:
This was a prospective multicentre cohort study, which involved universal testing for SARS-CoV-2 infection. On the 3rd June 2020, we changed our policy from testing only those women with signs and symptoms of COVID-19 infection to offering testing to all pregnant women admitted for delivery for SARS-CoV-2 using reverse transcription-polymerase chain reaction of nasopharyngeal swabs. The study period was the first month of implementation from 3rd June 2020 to 2nd July 2020.
This clinical pathway was approved by the North Wales clinical advisory group. This group was created during the early phase of the pandemic to enable the Health Board to be responsive to the clinical governance requirements to changing clinical pathways and delivery of care. It met daily initially to offer a multidisciplinary clinical consensus on changes to clinical pathways ensuring compliance with the best available evidence.
Women with scheduled admissions for induction of labour or elective caesarean sections were tested 24 -72 hours before admission at preoperative visits or at designated drive-through testing centres using a polymerase chain reaction-based platform (Mast Seegene) with a 24-hour turnaround time. Women with unscheduled admissions underwent testing with a rapid polymerase chain reaction-based platform (Cepheid Gene Xpert®) with a 4-hour turnaround time. These tests were performed alongside ongoing universal screening of patients for signs and symptoms of COVID-19 infection including fever, cough and loss or change in taste or smell.
Results:
Between 3rd June and 2nd July 2020, a total of 496 pregnant women delivered across the 3 maternity units. All women were screened on admission for symptoms of COVID-19. The results of SARS-CoV-2 testing are presented in table 1.
The overall prevalence of SARS-CoV-2 infection in pregnant women in North Wales was 2.74% with an asymptomatic prevalence of 1.89%. 69.23% of women positive for SARS-CoV-2 at delivery were asymptomatic (figure 1).
All women had mild disease. Amongst those with signs and symptoms, fever and cough were the most frequently reported. One woman reported household contact with an infected individual. All asymptomatic women were afebrile on admission and did not develop any signs or symptoms of COVID-19 during their period of admission. There were no cases of health care associated COVID-19 infections in any of the 3 maternity units during the study period.
Discussion
North Wales was the first region in Wales, and one of the first in the UK, to implement universal SARS-CoV-2 testing for pregnant women attending for delivery. Our study found that pregnant women infected with SARS-CoV-2 are often asymptomatic in keeping with other similar studies with universal testing7,8. This corroborates the observation that pregnant women with SARS-CoV-2 infection on admission are not reliably identified using symptom screening alone9. COVID-19 is a major public health threat and it is reasonable to expect that asymptomatic carriers will present for care, and potentially shed the virus and infect others10.
One of our units had higher prevalence than London with an East London maternity unit reporting an overall prevalence of 3.9%8. That study was conducted 4 weeks before our study and may be explained by the later onset of the disease in North Wales. North Wales was still in a period of COVID-19 related restrictions during this study. Schools reopened on the 29th June and two households in Wales were not allowed to meet indoors until 6th July.
Interesting, within North Wales, there was wide variation in the prevalence across 3 maternity units ranging from 1.68% to 4.43%. A study looking at prevalence in 2 hospitals in Philadelphia showed that prevalence differed between those 2 hospitals11. Betsi Cadwaladr University Health Board is the largest health organisation in Wales providing care for a population of around 694,000 people across the six principal areas of North Wales (Anglesey, Conwy, Denbighshire, Flintshire, Gwynedd and Wrexham) as well as some parts of Mid Wales, Cheshire and Shropshire. The regional demographics vary widely from densely populated towns such as Wrexham to rural areas in Gwynedd which may account for our local prevalence variance.
The reported prevalence of asymptomatic SARS-CoV-2 infection amongst pregnant populations vary from 0 – 15.5%11, 12, 13. Some international centres abandoned their protocols of universal testing when they identified low prevalence in their pregnant population. A trial period of universal testing may help determine whether such an approach makes sense for an individual unit.
Universal testing for all pregnant women upon admission for delivery has value for many reasons. It enables the identification of asymptomatic carriers of SARS-CoV-2 so that robust infection control measures can be put in place. Patients can be appropriated cohorted into groups of known positives, known negatives and those awaiting results. It allows more focussed use of personal protective equipment.
Maternal infection status allows informed management decisions of the new-born to minimise infection from droplet transmission.
Strengths of this study are the multicentre design and the number of patients included in the testing pathway. This represents one of the largest study population in published data of universal testing in pregnant women.
A potential weakness is that we did not test 100% of admissions. This was due to a small number of women declining testing and some missed opportunities for testing during the initial implementation of the policy. Since then, we have continued with universal testing and now have consistently near 100% of testing uptake.
It is important to note that universal testing for SARS-CoV-2 in obstetric units has mixed effects on maternal psychological experience. In one study, women who tested positive reported negative in-hospital experiences secondary to perceived lack of provider and partner support and neonatal separation after birth14. Healthcare staff feel more secure and generally viewed policies of universal testing favourably14. Ongoing patient experience evaluation of new testing protocols is paramount to balance staff and patient safety with quality and experience of care.
Conclusion:
Pregnant women with SARS-CoV-2 infection are not reliably identified using symptom and temperature screening alone as most infected women are asymptomatic on admission. The prevalence of maternal infection and asymptomatic carrier rates vary based on geographic differences in disease prevalence. It is suggested that a trial period of universal testing may help determine whether such an approach is appropriate for an individual maternity unit. Any new clinical pathway involving universal SARS-CoV-2 testing should have continual monitoring of clinical effectiveness and patient experience evaluation.
Disclosures of interests: No author has any interests to declare.
Contribution to authorship:
Hemant Maraj’s roles started at inception of the study and gaining clinical pathway approval at the health board’s clinical advisory group. He was involved in all aspects of carrying out the study, planning, analysing and writing up the final paper.
Deepannita Bhattacharjee was involved in developing the clinical pathway, analysing and writing up the paper.
Neha Jinsiwale was involved in data collection, maintaining integrity of the data, data analysis and writing up the paper.
Acknowledgements:
Nia Morris
NHS Librarian and Library Services Manger
John Spalding Library
Wrexham Medical Instiute
Wrexham LL13 7YP
Nia assisted with literature search and EndNote referencing.
Bethan Evans
Labour Ward Clinical Lead Midwife
Wrexham Maelor Hospital
Bethan Evans assisted with data collection at Wrexham Maelor Hospital
Joanna Kelly
Labour Ward Clinical Lead Midwife
Glan Clwyd Hospital
Joanna Kelly assisted with data collection at Glan Clwyd Hospital
Lorraine Gardner
Maternity Matron
Glan Clwyd Hospital
Lorraine Gardner assisted with data collection at Glan Clwyd Hospital
Eleri Pritchard
Labour Ward Clinical Lead Midwife
Ysbyty Gwynedd
Eleri Pritchard assisted with data collection at Ysbyty Gwynedd
Details of ethical approval:
Ethical approval was not required for this study as it was approved as a clinical pathway. This clinical pathway was approved by the North Wales clinical advisory group. This group was created during the early phase of the COVID-19 pandemic to enable the Health Board to be responsive to the clinical governance requirements to changing clinical pathways and delivery of care. It offered a multidisciplinary clinical consensus on changes to clinical pathways ensuring compliance with the best available evidence.
Funding:
There was no funding for this study. Funding for the clinical pathway was provided by Betsi Cadwaladr University Health Board and Public Health Wales.
References:
1. Organization WH. Novel coronavirus - China. 2020. www.who.int/csr/don/12-january-2020-novel-coronaviruschina/en/.
2. Smith V SD, Warty R, et al. . Maternal and neonatal outcomes associated with COVID-19 infection: A systematic review. PLOS ONE 2020;15(6):e0234187.
3. Royal College of Obstetricians and Gynaecologists. Coronavirus (COVID-19) Infection in pregancy. Guideline. 2020 14 October 2020. Version 12.
4. Lauer S.A. GKH, Bi Q, et al. The incubation period of coronavirus disease 2019 (COVID-19) from publicly reported confirmed cases: Estimation and application. Annals of Internal Medicine. 2020;172:577-82.
5. He X LE, Wu P, et al. Temporal dynamics in viral shedding and transmissibility of COVID-19. Nature Medicine. 2020;26:672-75.
6. Royal College of Obstetricians and Gynaecologists. Principles for the testing and triage of women seeking maternity care in hospital settings, during the COVID-19 pandemic.; 2020 10 August 2020. Version 2.
7. Breslin N, Baptiste C, Gyamfi-Bannerman C, Miller R, Martinez R, Bernstein K, et al. Coronavirus disease 2019 infection among asymptomatic and symptomatic pregnant women: two weeks of confirmed presentations to an affiliated pair of New York City hospitals. American Journal of Obstetrics and Gynecology MFM. 2020;2 (2 Supplement) (no pagination)(100118).
8. Abeysuriya S, Wasif S, Counihan C, Shah N, Iliodromiti S, Cutino-Moguel MT, et al. Universal screening for SARS-CoV-2 in pregnant women at term admitted to an East London maternity unit. European Journal of Obstetrics and Gynecology and Reproductive Biology. 2020;252:444-6.
9. Miller ES, Grobman WA, Sakowicz A, Rosati J, Peaceman AM. Clinical implications of universal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing in pregnancy. Obstetrics and Gynecology. 2020;136(2):232-4.
10. Zou L RF, Huang M, et al. SARS-CoV-2 viral load in upper respiratory specimens of infected patients. . New England Journal of Medicine. 2020;382:1177-9.
11. Bender WR, Hirshberg A, Coutifaris P, Acker AL, Srinivas SK. Universal testing for severe acute respiratory syndrome coronavirus 2 in 2 Philadelphia hospitals: carrier prevalence and symptom development over 2 weeks. American Journal of Obstetrics and Gynecology MFM. 2020;2 (4 Supplement) (no pagination)(100226).
12. Snyman LC, Molokoane F, Seopela L, Mopane N, Mojela M. First results of universal SARS-CoV-2 virus testing of asymptomatic pregnant patients presenting for antenatal care at the Kalafong Provincial Tertiary Hospital. Obstetrics and Gynaecology Forum. 2020;30(2):19-21.
13. Šterbenc A, Sršen TP, Lučovnik M, Šimic MV, Steblovnik L, Vodušek VF, Druškovič M, Kavšek G, Poljak M, Bregar AT. Usefulness of COVID-19 screen-and-test approach in pregnant women: an experience from a country with low COVID-19 burden. Journal of perinatal medicine. 2020 Oct 22;1(ahead-of-print).
14. Bender WR, Srinivas S, Coutifaris P, Acker A, Hirshberg A. The Psychological Experience of Obstetric Patients and Health Care Workers after Implementation of Universal SARS-CoV-2 Testing. American Journal of Perinatology. 2020;37(12):1271-9.
Table 1
Number of women tested and prevalence of SARS-CoV-2 infection among 3 maternity units in North Wales (homebirths excluded).