INTERCOVID: A prospective cohort study of the effects of COVID-19 
in pregnancy and the neonatal period

Coordinated by the INTERGROWTH-21st Team at the University of Oxford

INTERCOVID is a large, multi-national, prospective cohort study with the aim of assessing the effect of COVID-19 in pregnancy on maternal, fetal and neonatal outcomes worldwide. 

Although it is generally believed that pregnant women with COVID-19 are at similar risk to the general population, there are limited data available, principally from small case series without controls, which cannot answer fundamental questions relating to the effects of the disease in pregnancy.  We therefore plan to provide women, families, health care providers and policymakers with high-quality evidence regarding the effects of COVID-19 on maternal, fetal and neonatal outcomes. The information is needed quickly and at scale to optimise maternal and newborn care, reduce maternal anxiety, inform decision-making about the allocation of resources, and guide the process toward social adaptation. 

In the INTERCOVID Study, ‘exposed’ cases are defined as pregnant women with: a) laboratory confirmed COVID-19; b) radiological pulmonary findings suggestive of COVID-19; c) maternal symptoms compatible with COVID-19, or d) absence of symptoms, whilst in close interaction with a person(s) with confirmed COVID-19. 

Each ‘exposed’ case is compared with two ‘non-exposed’ pregnant women, considered as representative of the pregnant population at each study site.  Both ‘exposed’ and ‘non-exposed’ women will be recruited at any stage of pregnancy; women and their babies will be followed up until hospital discharge post-delivery. We will also conduct a nested case/non-case analysis to identify either risk factors or effect modifiers of the outcomes. Primary outcomes will be two unweighted indices: ‘maternal morbidity index’ and ‘severe neonatal morbidity index;’ individual component of the indices will be secondary outcomes.

Assuming that COVID-19 in pregnancy increases the risk of a common outcome, such as preterm birth, from 10% to 15%, it is possible to have 80% power with 500 ‘exposed’ women and 1000 ‘non-exposed’ women (1:2 ratio). Our Data Monitoring Group will evaluate these estimations in interim analyses. We expect that recruitment will take place during 6 months at most. We are using the same data collection forms and data management system as in all INTERGROWTH-21st Project studies (MedSciNet, London, UK). All data will be entered locally into the online system with its built-in extensive quality control facility. Ethical approval has already been obtained from the Oxford Tropical Research Ethics Committee (OxTREC), ref no 526-20.

The study commenced field preparations on 20 April 2020 and recruitment started immediately. Already, 62 medical institutions in 29 countries have agreed to participate. More are welcome to join us by contacting

The translational value of the INTERCOVID Study is that we will be collecting invaluable baseline outcome data, as recommended by the Pregnancy Research Ethics for Vaccines, Epidemics and New Technologies (PREVENT) Reportto inform risk-benefit analyses for future vaccine trials in pregnant women by providing “potential risk relationships between vaccination and adverse events”.  Failure to obtain that information runs the risk of pregnant women being denied priority access to a new vaccine or therapy, as has occurred so many times in the past.

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