Table 1.

Baseline characteristics of included studies.

Study	Study period	Study type	Study size	Mean age	Mean gestational age at birth
Zeng et al. (16)	January to February 2020	Cohort	3	NA	37
Dong et al. (17)	February 2020	Case Study	1	29	34
Chen et al. (18)	January 2020	Retrospective	9	29.89	37.11
Zhu et al. (19)	January to February 2020	Retrospective	9	30.89	35.11
Khan et al. (20)	January to February 2020	Case Series	17	29.29	37.82
Yin et al. (21)	January to February 2020	Cohort	17	31	37
Liu et al. (22)	January to February 2020	Retrospective	18	31	38.6
Chen et al. (23)	March 2020	Case Series	4	29	37.75
Alzamora et al. (24)	March 2020	Case Study	1	41	33
Xiong et al. (25)	January 2020	Case Study	1	25	33
Yang et al. (26)	January to March 2020	Cohort	13	30.2	38.2
Hantouchzadeh et al. (27)	March 2020	Retrospective	9	34.86	30
Qiancheng et al. (28)	January to March 2020	Cohort	22	30	38
Hu et al. (29)	January to February 2020	Case Series	7	32.71	38.71
Lu et al. (30)	February 2020	Case Study	1	22	38
Yan et al. (31)	January to March 2020	Retrospective	99	30.8	38
Ferrazzi et al. (32)	March 2020	Retrospective	24	30.9	NA
Zeng et al. (33)	March 2020	Retrospective	6	NA	NA
Iqbal et al. (34)	April 2020	Case Study	1	34	NA
Yang et al. (35)	January 2020	Case Series	7	NA	36.71
Wu et al. (36)	December 2019 to March 2020	Retrospective	20	33.35	31.87
Zhang et al. (37)	January to March 2020	Observational	18	29.11	38.4
Liu et al. (38)	March 2020	Retrospective	21	31	NA
Lee et al. (39)	January 2020	Case Study	1	28	37
Li et al. (40)	January to February 2020	Retrospective	16	30.9	38
Ibrahim (41)	February 2020	Retrospective	6	NA	NA
Semeshkin et al. (42)	May 2020	Observational	20	NA	NA
Liu et al. (43)	January to February 2020	Case Series	3	32.67	39
Adhdam et al. (44)	March 2020	Case Study	1	NA	NA