Table 2.
Hazard ratio of a positive SARS‐CoV‐2 test during pregnancy among 1 033 698 a women in Norway between 15 and 45 years of age
| Follow‐up period | Pregnancy status | Follow‐up time in days | No. of positive tests | Hazard ratio (95% CI) | |
|---|---|---|---|---|---|
| Unadjusted | Adjusted b | ||||
| Complete follow‐up c | Non‐pregnant | 356,383 248 | 16 364 | 1.00 | 1.00 |
| Pregnant | 15 481 516 | 708 | 0.98 (0.91–1.05) | 0.99 (0.92–1.07) | |
| 1st trimester | 5 454 096 | 256 | 0.97 (0.86–1.10) | 0.98 (0.87–1.11) | |
| 2nd trimester | 5 787 833 | 271 | 0.99 (0.88–1.12) | 1.01 (0.90–1.14) | |
| 3rd trimester | 4 239 587 | 181 | 0.96 (0.83–1.11) | 0.97 (0.84–1.13) | |
| Wave 1 d | Non‐pregnant | 119 435 417 | 1977 | 1.00 | 1.00 |
| Pregnant | 5 198 569 | 87 | 1.01 (0.82–1.26) | 0.94 (0.76–1.17) | |
| 1st trimester | 1 746 753 | 24 | 0.87 (0.58–1.30) | 0.81 (0.54–1.21) | |
| 2nd trimester | 1 941 362 | 35 | 1.05 (0.75–1.46) | 0.97 (0.69–1.36) | |
| 3rd trimester | 1 510 454 | 28 | 1.13 (0.78–1.65) | 1.05 (0.72–1.53) | |
| Wave 2 e | Non‐pregnant | 236 947 831 | 14 387 | 1.00 | 1.00 |
| Pregnant | 10 282 947 | 621 | 0.97 (0.90–1.05) | 1.00 (0.92–1.08) | |
| 1st trimester | 3 707 343 | 232 | 0.98 (0.86–1.12) | 1.01 (0.88–1.15) | |
| 2nd trimester | 3 846 471 | 236 | 0.99 (0.87–1.12) | 1.02 (0.90–1.16) | |
| 3rd trimester | 2 729 133 | 153 | 0.93 (0.79–1.09) | 0.96 (0.82–1.12) | |
a
Excluded one person who tested positive before 1 March 2020.
b
Adjusted for age as a linear and squared term, country of birth, marital status, education, household income, diabetes, cerebrovascular disease, other cardiovascular disorders, immune deficiency, chronic lung disease, reduced immune function, neurological disorders, kidney failure, organ transplant, haematological cancer, and other types of cancer.
c
1 March 2020–28 February 2021.
d
1 March 2020–30 June 2020.
e
1 July 2020–28 February 2021.