Table 2

Description of participants contributing to the individual patient data meta-analysis

Study author (year), countryNumber of COVID-19 cases/total pregnanciesLive birthsAmong all pregnanciesAmong COVID-19 cases
Mean age (SD)% obese
(BMI ≥30)
Asymptomatic (%)Onset in trimester 1 (%)Onset in trimester 2 (%)Onset in trimester 3 (%)Unknown GA at onset (%)
Akelo and Tippett Barr (2021), Kenya106/156080525.62 (5.35)*37.7*1145134
Le Doare (2021), Uganda69/53251625.93 (5.72)4.0142543
Crovetto (2020), Spain, Cohort I173/92176133.17 (5.3)10.080.3100†
Poon (2021), China-Hong Kong25/15215533.00 (4.53)24.0428644
Crovetto (2020), Spain, Cohort II176/1304133231.90 (5.78)12.0059.10†0†14†86†
Bevilacqua and Laurita Longo (2020), Italy109/2465241333.74 (5.4)15.0‡51.4 7 7 850
Nachega (2021), Multi-country Africa349/44218330.54 (5.72)0.018§64§12§
Nunes (2021), South Africa139/78175630.90 (6.74)12.9¶222715
Sakowicz (2021), USA503/1773178832.22 (5.10)31.6**521731
Ahlberg et al (2020),19 Sweden156/2682271432.2 (5.07)15.6††68.603970
Kalafat et al (2020),22 Turkey77/36234627.15 (5.63)24.7100
Brandt (2020), USA60/16216130.90 (6.34)55.005950
  • *This study includes 12 participants with unknown age (all COVID-negative comparisons). Two COVID-19 cases had unknown symptom status.

  • †Antibody testing at ANC (Cohort I) and at labour and delivery (Cohort II) was the primary method of diagnosis, thus gestational age at COVID-19 onset is unknown for almost all observations.

  • ‡167 participants had missing BMI data (7%).

  • §Gestational age at COVID-19 onset was not recorded. We use trimester of hospital admission as a proxy. n=41 participants were missing trimester of hospital admission (12%).

  • ¶Approximately 1.4% of the COVID-19 case sample in this study (Nunes, 2021, South Africa) have unknown symptom status (n=2).

  • **Approximately 2% of the COVID-19 case sample in this study (Sakowicz, 2021, USA) have unknown symptom status (n=8).

  • ††100 participants had missing BMI data (4%).

  • ANC, antenatal care; BMI, body mass index; GA, gestational age.