Current evidence of SARS-CoV-2 vertical transmission: an integrative review

An integrative review was performed by two independent researchers, based on the literature available in the MEDLINE (via PubMed) and LILACS databases, using the descriptors “pregnancy” AND “COVID-19” AND “vertical transmission”. This search included case reports or case series published up until 17^th June 2020 in English or Portuguese. After reading the articles available in their entirety, those related specifically to the potential risks of vertical transmission of COVID-19 during pregnancy were selected. We initially found a total of 57 articles; 26 were carefully screened and 15 were finally selected.

RESULTS

Pregnancy can make women more susceptible to infections, especially by viral pathogens, given the various physiological and immunological changes that occur to maintain maternal-fetal balance. It is speculated that the fetus may be a possible target for COVID-19. Few studies (3 out of 15) in our analysis have found positive results for SARS-CoV-2 in fetal membranes, placenta, and in newborns right after birth. Additionally, no difference was noticed when comparing different modes of delivery, and seems reasonable to assume that pregnant women with stable clinical conditions can be encouraged for vaginal delivery.

CONCLUSION

Further studies with a great number of cases are warranted to elucidate whether the virus may be vertically transmitted to the fetus and if any maternal conditions can influence that. Our findings seem to demonstrate that vertical transmission is possible but quite unusual.

Pregnancy; Coronavirus Infections; Infectious Disease Transmission, Vertical

Author	Date of publication	Number of pregnant women (n)	Number of neonates (n)	Pregnancy												Neonates
Author	Date of publication	Number of pregnant women (n)	Number of neonates (n)	Amniotic fluid		Placenta tissues		Maternal Serum		Vaginal swab		Throat swab		Breastilk		Umbilical cord blood		Anal swab		Throat swab
				+	-	+	-	+	-	+	-	+	-	+	-	+	-	+	-	+	-
Fan et al.⁹	17 Mar 2020	2	2		2		2		2		2	2			2		2				2
Yang et al.¹⁰	10 Apr 2020	7	7		5							7					5				6
Xiong et al.¹¹	10 Apr 2020	1	1		1		1				1	1			1				1		1
Peng et al.¹²	11 Apr 2020	1	1		1		1				1	1			1		1		1		1
Liu et al.¹³	13 Apr 2020	19	19		19							10			10		19				19
Alzamora et al.¹⁴	18 Apr 2020	1	1					1				1					1			1
Yan et al.¹⁵	23 Apr 2020	116	100		10						6	65			12		10				86
Qiancheng et al.¹⁶	27 Apr 2020	28	23									*									23
Lu et al.¹⁷	30 Apr 2020	1	1									1					1				1
Kalafat et al.¹⁸	5 May 2020	1	1				1					1			1		1				1
Penfield et al.¹⁹	8 May 2020	11	11			3	8														11
Kuhrt et al.²⁰	8 May 2020	1	2									1									2
Mehta et al.²¹	16 May 2020	1	2									1								1	1
Pereira et al.²²	22 May 2020	60	23				6					60									23
Li et al.²³	17 Jun 2020	1	1		1		1		1		1	1			1		1				1
Total		251	195	0	39	3	20	1	3	0	11	152	0	0	28	0	41	0	2	2	178

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[1] CORRESPONDING AUTHOR: Isabela Karine Rodrigues Agra Faculdade de Medicina da Universidade Federal de Alagoas (Ufal) - Campus A. C. Simões, Av. Lourival Melo Mota s/n Tabuleiro dos Martins – Maceió – Alagoas - CEP: 57072-900 -Tel.: (82) 3214-1858 E-mail: agraisabela@gmail.com