Table. Maternal, Pregnancy, and Birth Characteristics by SARS-CoV-2 Test Positivity in Pregnant Women.
Characteristics | Maternal SARS-CoV-2 test status | ||||
---|---|---|---|---|---|
Positive test result | No positive test result (full cohort) | Standardized differencea | No positive test result (matched cohort)b | Standardized differencea | |
No. of mothersc | 2286 | 84 719 | 9137 | ||
No. of infantsc | 2323 | 85 836 | 9275 | ||
Maternal age at delivery, y | |||||
Mean (SD) | 31.4 (5.0) | 31.4 (4.9) | 0.003 | 31.5 (4.9) | −0.009 |
Median (IQR) [range] | 31.3 (28.0-34.8) [17.3 to 49.8] | 31.3 (28.2-34.7) [14.1 to 59.9] | 31.3 (28.1-34.8) [16.6 to 52.0] | ||
No. (%) | |||||
13-24 | 224 (9.6) | 7672 (8.9) | 0.024 | 865 (9.3) | 0.011 |
25-29 | 689 (29.7) | 25 926 (30.2) | −0.012 | 2734 (29.5) | 0.004 |
30-34 | 855 (36.8) | 32 343 (37.7) | −0.018 | 3437 (37.1) | −0.005 |
≥35 | 555 (23.9) | 19 886 (23.2) | 0.017 | 2239 (24.1) | −0.006 |
Missing data | 0 | 9 | −0.014 | 0 | 0 |
Parity, No. (%) | |||||
Nulliparous | 1001 (43.1) | 37 058 (43.2) | −0.002 | 3995 (43.1) | 0.000 |
Multiparous | 1321 (56.9) | 48 740 (56.8) | 0.002 | 5278 (56.9) | −0.001 |
Missing data | 1 | 38 | −0.001 | 2 | 0.012 |
Singletons, No. (%) | 2247 (96.7) | 83 532 (97.3) | −0.035 | 8988 (96.9) | −0.010 |
Multiple pregnancy, No. (%) | 76 (3.3) | 2304 (2.7) | 0.035 | 287 (3.1) | 0.010 |
Prepregnancy comorbidity, No. (%)d | 231 (9.9) | 8581 (10.0) | −0.002 | 850 (9.2) | 0.027 |
Gestational diabetes, No. (%) | 163 (7.0) | 4331 (5.0) | 0.083 | 592 (6.4) | 0.025 |
Body mass indexe | |||||
Mean (SD) | 26.0 (5.2) | 25.3 (5.0) | 0.132 | 25.9 (5.3) | 0.020 |
Median (IQR) [range] | 24.9 (22.3-28.9) [14.5 to 55.7] | 24.2 (21.8-27.8) [13.2 to 69.8] | 24.8 (22.1-28.7) [14.7 to 54.6] | ||
No. (%) | |||||
<18.5 | 36 (1.6) | 1949 (2.4) | −0.053 | 151 (1.7) | −0.006 |
18.5 to <25 | 1092 (48.7) | 44 481 (54.1) | −0.096 | 4433 (49.6) | −0.016 |
25 to <30 | 661 (29.5) | 22 558 (27.5) | 0.049 | 2615 (29.2) | 0.006 |
30 to <35 | 309 (13.8) | 8998 (10.9) | 0.087 | 1155 (12.9) | 0.025 |
≥35 | 144 (6.4) | 4190 (5.1) | 0.058 | 591 (6.6) | −0.007 |
Missing data | 81 | 3660 | −0.040 | 330 | −0.004 |
Educational level, No. (%), y | |||||
≤9 | 207 (10.8) | 5616 (7.9) | 0.089 | 761 (10.0) | 0.025 |
10-12 | 656 (34.2) | 25 090 (35.3) | −0.022 | 2632 (34.5) | −0.003 |
>12 | 1053 (55.0) | 40 287 (56.7) | −0.032 | 4241 (55.6) | −0.008 |
Missing data | 407 | 14 843 | 0.006 | 1641 | −0.005 |
Smoking status, No. (%) | |||||
Nonsmoker | 2201 (97.6) | 79 820 (96.3) | 0.073 | 8887 (97.9) | −0.050 |
Smoker | 55 (2.4) | 3048 (3.7) | −0.070 | 195 (2.1) | 0.018 |
Missing data | 67 | 2968 | −0.033 | 193 | 0.052 |
Birth country, No. (%) | |||||
Nordic | 1320 (62.6) | 56 127 (71.9) | −0.176 | 5345 (63.6) | −0.016 |
Non-Nordic Europe | 152 (7.2) | 5546 (7.1) | 0.003 | 591 (7.0) | 0.007 |
Middle East/Africa | 536 (25.4) | 12 429 (15.9) | 0.221 | 2142 (25.5) | 0.000 |
Other | 99 (4.7) | 3977 (5.1) | −0.018 | 332 (3.9) | 0.035 |
Missing data | 216 | 7757 | 0.009 | 865 | −0.001 |
Living with partner, No. (%) | |||||
Yes | 2101 (91.8) | 77 263 (91.7) | 0.015 | 8412 (92.0) | −0.009 |
No | 187 (8.2) | 6980 (8.3) | −0.003 | 736 (8.0) | 0.004 |
Missing data | 35 | 1593 | −0.027 | 127 | 0.012 |
Health care region, No. (%) | |||||
North | 117 (5.0) | 5536 (6.4) | −0.061 | 460 (5.0) | 0.004 |
Middle | 378 (16.3) | 12 516 (14.6) | 0.047 | 1512 (16.3) | −0.001 |
East | 850 (36.6) | 24 176 (28.2) | 0.181 | 3393 (36.6) | 0.000 |
West | 468 (20.1) | 19 473 (22.7) | −0.062 | 1872 (20.2) | −0.001 |
Southeast | 231 (9.9) | 9802 (11.4) | −0.048 | 924 (10.0) | −0.001 |
South | 279 (12.0) | 14 332 (16.7) | −0.134 | 1114 (12.0) | 0.000 |
Delivery hospital, No. (%) | |||||
Hospital with full neonatal intensive care unit | 838 (36.1) | 24 778 (28.9) | 0.154 | 2724 (29.4) | 0.143 |
Other unit | 1485 (63.9) | 61 058 (71.1) | −0.154 | 6551 (70.6) | −0.143 |
Antenatal corticosteroids administered because of preterm birth, No. (%) | 58 (2.5) | 1061 (1.2) | 0.193 | 104 (1.1) | 0.103 |
Onset of delivery, No. (%) | |||||
Spontaneous | 1490 (64.1) | 55 662 (64.8) | −0.015 | 6033 (65.0) | −0.019 |
Induction of labor | 563 (24.2) | 21 857 (25.5) | −0.028 | 2258 (24.3) | −0.003 |
Cesarean delivery | 270 (11.6) | 8317 (9.7) | 0.063 | 984 (10.6) | 0.032 |
Mode of delivery, No. (%) | |||||
Vaginal birth | 1828 (78.7) | 70 386 (82.0) | −0.083 | 7525 (81.1) | −0.061 |
Cesarean delivery | 495 (21.3) | 15 450 (18.0) | 0.083 | 1750 (18.9) | 0.061 |
Time from date of positive maternal SARS-CoV-2 test result to birth, d | |||||
Mean (SD) | 56.3 (62.6) | ||||
Median (IQR) [range] | 36 (5-85) [−7 to 284] | ||||
Infant sex, No. (%) | |||||
Male | 1157 (49.8) | 43 839 (51.1) | −0.025 | 4776 (51.5) | −0.034 |
Female | 1166 (50.2) | 41 997 (48.9) | 0.025 | 4499 (48.5) | 0.034 |
Gestational age | |||||
Mean (SD), d | 274.7 (15.1) | 277.0 (12.6) | −0.162 | 277.1 (12.6) | −0.170 |
Median (IQR) [range], d | 278 (270-284) [157 to 296] | 279 (272-285) [154 to 305] | 279 (272-285) [159 to 302] | ||
No. (%), wk | |||||
22 to <32 | 38 (1.6) | 675 (0.8) | 0.078 | 66 (0.7) | 0.086 |
32 to <35 | 90 (3.9) | 1742 (2.0) | 0.109 | 177 (1.9) | 0.118 |
35 to <42 | 2194 (94.4) | 82 052 (95.6) | −0.053 | 8830 (95.2) | −0.034 |
≥42 | 39 (1.7) | 2042 (2.4) | −0.050 | 268 (2.9) | −0.081 |
Apgar score at 5 min, No. (%) | |||||
<7 | 48 (2.1) | 1300 (1.5) | 0.042 | 134 (1.5) | 0.047 |
<4 | 9 (0.4) | 248 (0.3) | 0.017 | 29 (0.3) | 0.013 |
Missing data | 32 | 601 | 0.067 | 52 | 0.083 |
Birth weight, g | |||||
Mean (SD) | 3436 (628) | 3502 (559) | −0.111 | 3495 (558) | −0.099 |
Median (IQR) [range] | 3485 (3100-3826) [540 to 5860] | 3522 (3185-3855) [360 to 6040] | 3525 (3190-3840) [505 to 5800] | ||
No. (%) | |||||
Large for gestational age | 84 (3.7) | 3144 (3.7) | −0.002 | 328 (3.5) | 0.004 |
Small for gestational age | 54 (2.4) | 1864 (2.2) | 0.010 | 246 (2.7) | −0.021 |
Missing data | 52 | 799 | 0.105 | 31 | 0.170 |
Abbreviation: IQR, interquartile range.
Standardized differences were calculated according to Austin.30
Ten exposed infants (all twins) were not possible to match in a 1:4 ratio.
Numbers of mothers and infants differ because of multiple births.
Prepregnancy comorbidity included diabetes, hypertension, cardiovascular disease, kidney disease, and lung disease.
Body mass index is calculated as weight in kilograms divided by height in meters squared.