Table 1

Study characteristics

Data sourceStudyLocationDates of data collectionRecruitment strategy*COVID-19 case definitionCOVID-negative comparison group
Prospective pregnancy cohort studiesAkelo and Tippett Barr (2021)KenyaJuly 2020 to May 2021, with follow-up through deliveryabcdePositive PCR testNegative PCR test
Le Doare (2021)UgandaSeptember 2020 to July 2021, with follow-up through deliveryabcPositive PCR or diagnosed probable COVID-19Negative PCR or antibody test (recruitment)
Crovetto (2020), Cohort ISpainMarch to May 2020, with follow-up through deliveryabPositive PCR or antibody test†Negative antibody test (ANC) and negative PCR test (delivery)
Other cohort studiesPoon (2021)China-Hong KongMarch 2020 to January 2021abcdePositive PCR test or antibody testNegative antibody test (ANC and delivery)
Crovetto (2020), Cohort IISpainMarch to May 2020bPositive PCR or antibody test‡Negative antibody test and PCR test (delivery)
Bevilacqua and Laurita Longo (2020)ItalyFebruary 2020 to March 2021bcdePositive PCR testNegative PCR test
Nachega (2021)Africa§ (6 countries)March to October 2020cePositive PCR testNegative PCR (hospital controls)
Nunes (2021)South AfricaApril to September 2020cdePositive PCR testNegative PCR test
Sakowicz (2021)Chicago, USAMarch 2020 to February 2021bdePositive PCR testNegative PCR test (at delivery)
Ahlberg et al 19 SwedenMarch to July 2020bdPositive PCR test or antibody testNegative PCR test (at delivery)
Kalafat et al 22 TurkeyMay to June 2020bdPositive PCR testNegative PCR test
Brandt (2020)New Brunswick, USAMarch to June 2020bdPositive PCR testNegative PCR test
  • *Recruitment strategies categorised as: (a) universal screening at antenatal care, (b) universal screening at delivery, (c) hospitalised for COVID-19, (d) other COVID-19 testing for clinical concern, (e) tested based on admission for other medical reasons.

  • †Antibody tests were administered to women recruited at first trimester or early second trimester ANC. Participants were also administered follow-up PCR tests at labour and delivery.

  • ‡Antibody tests were administered to all participating women at labour and delivery; most participants (85%) also received a PCR test at labour and delivery.

  • §Democratic Republic of Congo, Ghana, Kenya, Nigeria, South Africa, Uganda.

  • ¶10 asymptomatic patients were tested a day during the recruitment period.

  • ANC, antenatal care.