Table 1. Characteristics of included studies.
| Study (year) | Country | Delivery mode | Number of neonates tested | Samples (time of sample collection) | Sample test results |
|---|---|---|---|---|---|
| Alzamora et al 5 (2020) | Peru | Cesarean delivery | 1 | Serum sample IgG, IgM (at birth); neonatal nasopharyngeal swab (16 hours after delivery and repeated 48 hours later) | IgG, IgM negative; nasopharyngeal swab positive |
| Chen et al 4 (2020) | China | Cesarean delivery | 6 | Amniotic fluid (at the time of delivery); cord blood (immediately after delivery); neonatal throat swab (immediately after delivery); breastmilk (after first lactation) | Negative |
| Chen et al 18 (2020) | China | Cesarean delivery | 1 | Amniotic fluid (at the time of delivery); cord blood (immediately after delivery); placenta (immediately after delivery); breastmilk (day 1–5 postpartum); neonatal throat swab (day 1–7 after birth); stool (day 1–7 after birth) | Negative |
| Chen et al 14 (2020) | China | Cesarean delivery | 3 | Placenta (immediately after delivery); neonatal throat swab (specific time not reported) | Negative |
| Dong et al 9 (2020) | China | Cesarean delivery | 1 | Breastmilk (6 days after delivery); serum sample IgG, IgM (at 2 hours of age and 15 days of age); nasopharyngeal swab (5 tests from 2 hours to 16 days of age) | IgG 140.32 AU/mL, IgM 45.83 AU/mL (2 hours of age); IgG 69.94 AU/mL, IgM 11.75 AU/mL (15 days of age). All RT-PCR tests results were negative |
| Khan et al 19 | China | Vaginal delivery | 3 | Nasopharyngeal swab (time of collection not reported) | Negative |
| Lee et al 20 | Korea | Cesarean delivery | 1 | Placenta, amniotic fluid, and cord blood (at delivery); two consecutive neonatal nasopharyngeal swab (time of collection not reported) | Negative |
| Lei et al 21 | China | Vaginal delivery (1), cesarean delivery (3) | 4 | Vaginal secretion (time of collection not reported); amniotic fluid (at the time of delivery); cord blood (at the time of delivery); breastmilk (time of collection not reported); neonatal nasal and throat swab (time of collection not reported) | Negative |
| Li et al 6 (2020) | China | Cesarean delivery | 1 | Neonatal throat swab (3 days after birth) | Positive (neonatal throat swab) |
| Li et al 22 (2020) | China | Cesarean delivery | 1 | Amniotic fluid, cord blood, placenta, and breastmilk (on the delivery day); infant's oropharyngeal swab, blood, feces, and urine samples (seven different times at day 1 and day 2 after birth) | Negative |
| Liu et al 23 (2020) | China | Cesarean delivery | 9 | Not reported | Negative |
| Liu et al 24 (2020) | China | Vaginal delivery (1), cesarean delivery (10) | 11 | Not reported | Negative |
| González et al 25 | Spain | Cesarean delivery | 1 | Not reported | Negative |
| Wang et al 26 | China | Cesarean delivery | 1 | Amniotic fluid (during delivery); placenta (during delivery); cord blood (during delivery); gastric juice (during delivery); neonatal throat swab (during delivery, day 3, 7, and 9 after cesarean delivery); neonatal stool samples (day 3 after cesarean delivery) | Negative |
| Xiong et al 27 | China | Vaginal delivery | 1 | Amniotic fluid, neonatal throat swab, and rectal swab (time of collection not reported); neonatal IgG and IgM antibodies (time of collection not reported) | Negative |
| Yao et al 28 | China | Cesarean delivery | 1 | Neonatal blood sample (after delivery, day 1 after birth); neonatal nasal and throat swab (after delivery, day 1 and 9 after birth); anal swab (day 9 after birth) | Negative |
| Yu et al 7 (2020) | China | Cesarean delivery | 9 | Neonatal throat swab (at 36 hours after birth) | Negative (8), positive (1) |
| Zeng et al 8 | China | Cesarean delivery | 6 | Neonatal throat swab and blood sample (at birth); serum sample IgG, IgM (at birth) | Two had IgG and IgM higher than normal; three had elevated IgG but normal IgM levels. All RT-PCR test results were negative. |
| Zhang et al 29 | China | Cesarean delivery | 10 | Neonatal throat swab (after birth) | Negative |
| Zhou et al 30 | China | Cesarean delivery | 1 | Neonatal blood sample and throat swab (on the day of birth, four and seven days after birth) | Negative |
| Zhu et al 31 | China | Vaginal delivery (2), cesarean delivery (8) | 10 | Neonatal throat swab (day 1–9 after birth) | Negative (9), no data (1) |
| Zhuang et al 32 | China | Cesarean delivery | 1 | Breastmilk (day 5 after cesarean delivery); neonatal throat swab (day 5 after cesarean delivery) | Negative |
Abbreviations: IgG, immunoglobulin G; IgM, immunoglobulin M.
Note: Unless specified otherwise, all tests were real-time polymerase chain reaction.