High Rate of Chronic Villitis in Placentas of Pregnancies Complicated by Influenza A/H1N1 Infection

Table 3

Number of placentas with chronic villitis, divided by proven or suspected infection and grade of villitis.

	Villitis of any grade (𝑛, (%))	Villitis of grade 1 (𝑛)	Villitis of grade 2 (𝑛)	Villitis of grade 3 (𝑛)
PCR confirmed cases (𝑛=5)	3 (60)	3	0	0
Clinical cases (𝑛=10)	4 (40)	2	2	0
Total (𝑛=15)	7 (47)	5	2	0
Historic cohort* (𝑛=271)	65 (24)	46	16	3

∗Historic cohort consists of placentas of women with uncomplicated pregnancy and vaginal delivery, as described in Section 2 [11].