Supplemental Table.

Modified Newcastle-Ottawa scale for assessing quality of cohort or case series studies

Author	Year	Representativeness of exposed cohort	Exposure assessment	Outcome assessment	Adequacy of length of time before follow-up	Adequacy of follow-up of cohorts	Methodological quality
Breslin, et al76	April 2020	★	★	★	★	★	High
Breslin, et al77	May 2020	★	★	★	★	★	High
Cao, et al59	April 2020		★		★		Low
Chen, et al10	February 2020	★	★	★	★		Moderate
Ferrazzi, et al78	April 2020	★	★	★	★	★	High
Hu, et al60	April 2020		★	★	★	★	Moderate
Khan, et al38	April 2020	★	★	★	★		Moderate
Liu, et al40	March 2020	★		★	★		Low
Nie, et al63	March 2020	★	★	★	★		Moderate
Penfield, et al79	May 2020	★	★	★	★	★	High
Patane, et al30	May 2020	★	★	★	★	★	High
Pierce-Williams, et al80	May 2020	★	★		★	★	Moderate
Qiancheng, et al64	April 2020	★	★	★	★	★	High
Yan, et al11	April 2020	★	★	★	★		Moderate
Yang, et al65	April 2020	★	★	★	★	★	High
Yin, et al66	April 2020	★	★	★	★		Moderate
Yu, et al56	March 2020	★	★	★	★	★	High
Zeng, et al26	March 2020		★	★	★		Low
Zeng, et al67	March 2020	★	★	★	★	★	High
Zhu, et al9	Feb 2020		★	★	★		Low
Lokken, et al81	May 2020	★	★	★			Low
London, et al82	May 2020	★	★	★	★		Moderate
Mulvey, et al83	April 2020		★				Low
Baergen, et al84	May 2020	★	★	★	★		Moderate
Buonsenso, et al49	May 2020		★	★	★	★	Moderate
Chen, et al68	April 2020		★	★	★		Low
Chen, et al69	March 2020	★	★	★	★		Moderate
Govind, et al86	May 2020	★	★	★	★		Moderate
Knight, et al12	May 2020	★	★	★	★	★	High
Liao, et al70	April 2020	★	★	★	★	★	High
Liu, et al71	May 2020	★	★	★	★	★	High
Pereira, et al87	May 2020	★	★	★	★		Moderate
Qadri, et al89	May 2020	★	★	★	★		Moderate
Wu, et al72	May 2020	★	★	★	★	★	High
Wu, et al73	April 2020	★	★		★		Low
Yang, et al74	April 2020		★		★		Low
Yang, et al75	May 2020	★	★	★	★		Moderate
Shanes, et al88	May 2020	★	★	★			Low
Vintzileos, et al90	April 2020	★	★	★	★		Moderate

Questions:

• 1.
  Did the patients represent the whole cases of the medical center? Cases included represented the general population of COVID-19 pregnant women.
• 2.
  Was the diagnosis correctly made? COVID-19 was diagnosed by viral PCR.
• 3.
  Was the outcome correctly ascertained? Clear description of adequate methodology of testing for COVID-19 in fetus or neonate was provided.
• 4.
  Was follow-up long enough for outcomes to occur? Adequate follow-up time was reported.
• 5.
  Were all important data cited in the report? Testing was repeated at least 2 times on 2 separate occasions.
• Methodological quality: high=5 stars, moderate=4 stars, low=3 or fewer stars.

Kotlyar. Vertical transmission of COVID-19: a systematic review and meta-analysis. Am J Obstet Gynecol 2021.