Description of participants contributing to the individual patient data meta-analysis
| Study author (year), country | Number of COVID-19 cases/total pregnancies | Live births | Among all pregnancies | Among 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), Kenya | 106/1560 | 805 | 25.62 (5.35)* | – | 37.7* | 1 | 14 | 51 | 34 |
| Le Doare (2021), Uganda | 69/532 | 516 | 25.93 (5.72) | – | 4.0 | 1 | 42 | 54 | 3 |
| Crovetto (2020), Spain, Cohort I | 173/921 | 761 | 33.17 (5.3) | 10.0 | 80.3 | – | – | – | 100† |
| Poon (2021), China-Hong Kong | 25/152 | 155 | 33.00 (4.53) | – | 24.0 | 4 | 28 | 64 | 4 |
| Crovetto (2020), Spain, Cohort II | 176/1304 | 1332 | 31.90 (5.78) | 12.00 | 59.1 | 0† | 0† | 14† | 86† |
| Bevilacqua and Laurita Longo (2020), Italy | 109/2465 | 2413 | 33.74 (5.4) | 15.0‡ | 51.4 | 7 | 7 | 85 | 0 |
| Nachega (2021), Multi-country Africa | 349/442 | 183 | 30.54 (5.72) | – | 0.0 | 6§ | 18§ | 64§ | 12§ |
| Nunes (2021), South Africa | 139/781 | 756 | 30.90 (6.74) | – | 12.9¶ | 2 | 22 | 71 | 5 |
| Sakowicz (2021), USA | 503/1773 | 1788 | 32.22 (5.10) | – | 31.6** | 5 | 21 | 73 | 1 |
| Ahlberg et al (2020),19 Sweden | 156/2682 | 2714 | 32.2 (5.07) | 15.6†† | 68.6 | 0 | 3 | 97 | 0 |
| Kalafat et al (2020),22 Turkey | 77/362 | 346 | 27.15 (5.63) | – | 24.7 | – | – | – | 100 |
| Brandt (2020), USA | 60/162 | 161 | 30.90 (6.34) | – | 55.0 | 0 | 5 | 95 | 0 |
*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.