Placental infections with histologically confirmed Plasmodium falciparum are associated with adverse birth outcomes in India: a cross-sectional study

Table 4 Placental histology features by category of histopathological infection (independent of Plasmodium species)

Placental features	No^†	Past^††	Past vs	Active^♣	Active vs No inf.	Acute Inf.	Acute vs No inf.	Chronic Inf.	Chronic vs No inf.
	Inf.	Inf.	No inf.	Inf.	Active vs No inf.	Acute Inf.	Acute vs No inf.	Chronic Inf.	Chronic vs No inf.
	n = 454	n = 14	p-value	n = 38	p value	n = 20	p value	n = 18	p value
Syncytial Knots
Normal, n (%)	414 (91.2)	8 (57.1)	<0.001	18 (47.4)	<0.0001	12 (60.0)	0.0003	6 (33.3)	<0.0001
Increased (>1/3), n(%)	40 (8.8)	6 (42.9)		20 (52.6)		8 (40.0)		12 (66.7)
Fibrinoid necrosis
Absent, n (%)	393 (86.5)	7 (50.0)		27 (71.1)		20 (100.0)		7 (38.9)
Focal, n (%)	58 (12.8)	6 (42.9)	0.0001	9 (23.6)	0.003	0	0.15	9 (50.0)	<0.0001
Diffuse, n (%)	3 (0.7)	1 (7.1)		2 (5.3)		0		2 (11.1)
Calcification
Absent, n (%)	416 (91.6)	9 (64.3)		29 (76.3)		20 (100.0)		9 (50.0)
Focal, n (%)	31 (6.8)	4 (28.6)	0.002	7 (18.4)	0.008	0	0.30	7 (38.9)	<0.0001
Diffuse, n (%)	7 (1.6)	1 (7.1)		2 (5.3)		0		2 (11.1)
IVS * PMN cell
Absent, n (%)	340 (74.9)	13 (92.9)		26 (70.3)		14 (70.0)		12 (70.6)
Mild, n (%)	80 (17.6)	1 (7.1)	0.47	9 (24.3)	0.75	4 (20.0)	0.93	5 (29.4)	0.45
Moderate, n (%)	33 (7.3)	0		2 (5.4)		2 (10.0)		0
Severe, n (%)	1 (0.2)	0		0		0		0
IVS * monocyte
Absent, n (%)	358 (78.8)	11 (78.6)		3 (7.9)		1 (5.0)		2 (11.1)
Mild, n (%)	74 (16.3)	3 (21.4)	0.63	24 (63.2)	<0.0001	12 (60.0)	<0.0001	12 (66.7)	<0.0001
Moderate, n (%)	22 (4.9)	0		10 (26.3)		6 (30.0)		4 (22.2)
Severe, n (%)	0	0		1 (2.6)		1 (5.0)		0
IVS * fibrin
Absent, n (%)	134 (29.5)	0		4 (10.5)		4 (20.0)		0
Mild, n (%)	268 (59.0)	5 (35.7)	<0.001	25 (65.8)	0.0002	15 (75.0)	<0.47	10 (55.6)	<0.0001
Moderate, n (%)	52 (11.5)	9 (64.3)		8 (21.1)		1 (5.0)		7 (38.9)
Severe, n (%)	0	0		1 (2.6)		0		1 (5.5)

All are column %. Active infection group includes 1 missing result for IVS PMN cell score. ^†histology classification. No-infection = parasite and pigment absent, Acute infection = parasite present, ±pigmented monocytes, ± few spots pigment in fibrin; Chronic infection = parasite present, ±pigmented monocytes, +pigment in fibrin; Active infection = acute + chronic infection; Past infection = no parasites, only pigment present; ^††includes 2 cases corresponding to P. vivax infection; ^♣pooled histology classified acute & chronic infection. Abbreviations: ^*IVS = intervillous space; PMN = polymorphonuclear.

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