Table 1.

Basic information about the included studies

Author, year (Ref)	Country	Setting	Time period	Study design	Sample size	Mean age (Year) (Range)	Mean gestational age (Week) (Range)
Chen et al. , 2020-c (14)	China	Renmin hospital	From January 30-February 23, 2020	Case series	17	29.5	$<$37 = 3 $>$37 = 14
Chen et al. , 2020-a (13)	China	Maternal and child hospital of Hubei province	From January 20-February 10, 2020	Case series	5	28.4 (25-31)	38-40
Chen et al. , 2020-b (22)	China	Zhongnan hospital	From January 20-January 31, 2020	Case series	9	32.5 (26-40)	36-39
Khan et al. , 2020 (25)	China	Renmin hospital	From January 28-March 1, 2020	Case series	3	29.3 (27-33)	(34-39)
Li et al. , 2020 (24)	China	Hubei provincial maternal and child health center	From January 24-February 29, 2020	Case-control	16	30.9	38
Liu et al. , 2020-c (28)	China	Hospitals outside of Wuhan	From December 8, 2019-February 25, 2020	Case series	13	29.6 (22-36)	(25-38)
Liu et al. , 2020-b (26)	China	Multicenter	From January 27-February 14, 2020	Case-control	41	30.5 (22-42)	NR
Liu et al. , 2020-a (27)	China	Union hospital	From January 20, 2020-February 10, 2020	Case series	15	32 (23-40)	32 (12-38)
Yu et al. , 2020 (30)	China	Tongji hospital	From January 1-February 8, 2020	Case series	7	32 (29-34 )	39 (37-41)
Zhu et al. , 2020 (31)	China	Multicenter (five hospitals)	From January 20-February 5, 2020	Case series	9	29.5 (25-35)	(31-42)
NR: Not reported