Table 1. Maternal Illness Severity and Results of NP-PCR Testing and Antibody Concentrations.
| Characteristic | All (N = 83) | Asymptomatic (n = 50) | Disease | P value | |
|---|---|---|---|---|---|
| Mild (n = 25)a | Moderate to critical (n = 8) | ||||
| NP-PCR tested (mother), No. (%)b | 82 (99) | 49 (98) | 25 (100) | 8 (100) | >.99 |
| NP-PCR ever positive | 44 (54) | 15 (31) | 21 (84) | 8 (100) | <.001 |
| Reason for NP-PCR testing | |||||
| Routine admission screening | 52 (63) | 47 (96) | 5 (20) | 0 | <.001 |
| Symptoms | 27 (33) | 0 | 19 (76) | 8 (100) | |
| Otherc | 3 (4) | 2 (4) | 1 (4) | 0 | |
| Time between NP-PCR test and delivery, median (IQR), d | 1 (0-27) | 1 (0-1) | 27 (10-73) | 53 (44-73) | <.001 |
| Maternal IgM >0.48 arbitrary U/mL, No. (%) | 48 (58) | 28 (56) | 13 (52) | 7 (88) | .21 |
| Maternal IgM concentration, geometric mean (95% CI)d | 1.85 (1.43-2.39) | 1.39 (1.03-1.89) | 2.50 (1.42-4.39) | 3.33 (1.60-6.93) | .77 |
| Maternal IgG >0.48 arbitrary U/mL, No. (%) | 78 (94) | 46 (92) | 24 (96) | 8 (100) | .80 |
| Maternal IgG concentration, geometric mean (95% CI)d | 4.69 (3.57-6.14) | 3.92 (2.82-5.46) | 4.44 (2.67-7.38) | 15.27 (5.82-40.09) | .91 |
| Cord IgG >0.48 arbitrary U/mLe | 72 (92) | 44 (96) | 20 (83) | 8 (100) | .26 |
| Cord IgG concentration, geometric mean (95% CI)e,f | 4.23 (3.06-5.84) | 4.01 (2.77-5.83) | 3.09 (1.59-6.01) | 14.58 (4.26-49.84) | .44 |
| Transfer ratio, geometric mean (95% CI), %e,f | 0.90 (0.76-1.07) | 1.02 (0.85-1.23) | 0.70 (0.48-1.01) | 0.95 (0.45-2.01) | .34 |
Abbreviations: IQR, interquartile range; NP-PCR, nasopharyngeal polymerase chain reaction; U, units.
Mild disease in 21 of 25 cases was defined by symptoms reported in conjunction with NP-PCR testing. In the remaining 4 cases, women reported coronavirus disease 2019–consistent symptoms to obstetric caregivers prior to delivery, but testing was not done. In each case, routine NP-PCR screening results at the time of admission to labor floor were negative.
One asymptomatic woman declined routine admission NP-PCR screening.
Tested due to contact.
Only values >0.48 arbitrary U/mL included in the calculation of geometric mean.
Only includes infants born to IgG-seropositive mothers (maternal IgG >0.48 arbitrary U/mL).
Six of 78 infants born to IgG-seropositive mothers were seronegative (cord IgG ≤0.48 arbitrary U/mL); cord IgG concentration was set at 0.24 arbitrary U/mL for these 6 infants.