Summary of study time periods
| Study | COVID-19 period start | Comparison period start | COVID-19 period end | Comparison period end | COVID-19 period length (days) | Comparison period length (days) |
| Aboul-Nour 202118 | 3/20/20 | 3/20/19 | 5/20/20 | 5/20/19 | 61 | 61 |
| Agarwal 202019 | 3/1/20 | 6/1/19 | 5/15/20 | 2/29/20 | 75 | 273 |
| Altschul 20208 | 3/1/20 | 1/1/20 | 4/17/20 | 2/17/20 | 47 | 47 |
| Amukotuwa 202011 | 3/1/20 | 1/31/19 | 5/10/20 | 3/1/19 | 70 | 29 |
| Aref 202120 | 2/15/20 | 12/7/19 | 5/10/20 | 2/14/20 | 85 | 69 |
| Candelaresi 202121 | 3/9/20 | 3/9/19 | 4/16/20 | 4/16/19 | 38 | 38 |
| Chen 202122 | 1/1/20 | 1/1/18 | 9/30/20 | 12/31/19 | 273 | 729 |
| Cummings 202023 | 3/1/20 | 3/1/19 | 4/1/20 | 2/1/20 | 31 | 337 |
| D'Anna 202124 | 3/23/20 | 3/23/19 | 6/30/20 | 6/30/19 | 99 | 99 |
| Ghoreishi 202025 | 2/18/20 | 2/18/19 | 7/18/20 | 7/18/19 | 151 | 150 |
| Gu 202126 | 2/1/20 | 12/1/19 | 3/31/20 | 1/30/20 | 59 | 60 |
| Huo 202127 | 1/1/20 | 1/1/19 | 4/30/20 | 4/30/19 | 120 | 119 |
| Jasne 202028 | 3/1/20 | 2/1/20 | 4/28/20 | 4/28/20 | 58 | 87 |
| John 202016 | 3/1/20 | 3/1/19 | 5/10/20 | 5/10/19 | 70 | 70 |
| Katsanos 202029 | 3/17/20 | 3/1/19 | 4/30/20 | 3/16/20 | 44 | 381 |
| Kwan 202030 | 3/3/20 | 1/1/20 | 4/30/20 | 3/3/20 | 58 | 62 |
| Li 202131 | 1/23/20 | 2/3/20 | 4/8/20 | 4/17/20 | 76 | 74 |
| Luo 202132 | 1/1/20 | 1/1/19 | 5/31/20 | 5/31/19 | 151 | 150 |
| Mag Uidhir 202033 | 1/1/20 | 1/1/19 | 6/30/20 | 6/30/19 | 181 | 180 |
| Mitra 202034 | 3/26/20 | 3/26/19 | 4/23/20 | 4/23/19 | 28 | 28 |
| Naccarato 202035 | 3/9/20 | 3/9/19 | 4/9/20 | 4/9/19 | 31 | 31 |
| Nagamine 20209 | 3/1/20 | 3/1/19 | 4/30/20 | 4/3/19 | 60 | 33 |
| Neves-Briard 202017 | 3/30/20 | 3/30/19 | 5/31/20 | 5/31/19 | 62 | 62 |
| Padmanabhan 202036 | 3/15/20 | 3/15/19 | 4/14/20 | 4/14/19 | 30 | 30 |
| Paliwal 202037 | 2/7/20 | 11/1/19 | 4/30/20 | 2/6/20 | 83 | 97 |
| Plumereau 202038 | 2/29/20 | 2/28/19 | 5/10/20 | 5/10/19 | 71 | 71 |
| Rinkel 202039 | 3/16/20 | 10/21/19 | 5/3/20 | 12/8/19 | 48 | 48 |
| Rudilosso 202040 | 3/1/20 | 3/1/19 | 3/31/20 | 3/31/19 | 30 | 30 |
| Siegler 202041 | 3/1/20 | 10/1/19 | 4/15/20 | 2/29/20 | 45 | 151 |
| Tan 202142 | 1/24/20 | 1/24/19 | 3/10/20 | 3/10/19 | 46 | 45 |
| Tejada-Meza 202043 | 3/9/20 | 12/30/19 | 5/3/20 | 3/8/20 | 55 | 69 |
| Teo 202010 | 1/23/20 | 1/23/19 | 3/24/20 | 3/24/19 | 61 | 60 |
| Uchino 202044 | 3/9/20 | 1/1/20 | 4/2/20 | 3/8/20 | 24 | 67 |
| Velilla-Alonso 202145 | 3/14/20 | 3/14/19 | 5/14/20 | 5/14/19 | 61 | 61 |
| Wang 202046 | 3/12/20 | 12/1/19 | 6/30/20 | 3/11/20 | 110 | 101 |
| Yang 202047 | 1/23/20 | 12/1/19 | 3/7/20 | 1/14/20 | 44 | 44 |
| Zhang 202148 | 1/23/20 | 11/8/19 | 4/8/20 | 1/22/20 | 76 | 75 |
| Zini 202049 | 3/1/20 | 3/1/19 | 4/30/20 | 4/30/19 | 60 | 60 |
The COVID-19 and comparison period dates for each study are presented. The COVID-19 period was defined as the period of time occurring after the pandemic began, and the comparison period before the pandemic began. The length of each period in days for each study are also presented.