Table 4.

Placenta pathology and spontaneous preterm birth compared to iatrogenic preterm birth.

Pathology variable	SPTB (141) n (% YES) of variable	IPTB (84) n (% YES) of variable	p- value
Features of maternal vascular malperfusion
Small trimmed placenta for GA	66 (47%)	49 (59%)	0.229
Macroscopic pathological infarction	9 (6%)	9 (11%)	0.729
Microscopic pathological infarction	20 (14%)	26 (31%)	0.009
Decidual arteriopathy	16 (11%)	22 (26%)	0.014
Accelerated villous maturation	30 (21%)	43 (51%)	0.000
Increased syncytial knots	42 (30%)	52 (62%)	0.000
Distal villous hypoplasia	12 (9%)	29 (35%)	0.000
Increased extravillous trophoblast/fibrinoid islands	26 (18%)	28 (33%)	0.037
Increased perivillous fibrin	42 (30%)	46 (55%)	0.001
Features of abruption
Macroscopic abruption	15 (11%)	16 (19%)	0.243
Microscopic abruption	28 (20%)	20 (24%)	1.000
Acute placental abruption (both macro and micro)	10 (7%)	11 (13%)	0.422
Features of fetal vascular malperfusion
Thrombosis of cord vessels (microscopic)	2 (1%)	6 (7%)	0.075
Avascular villi	24 (17%)	28 (33%)	0.017
Chorionic plate/stem villus thrombosis	11 (8%)	10 (12%)	0.937
Villous-stromal karyorrhexis	22 (16%)	25 (30%)	0.038
Fetal vascular thrombosis (microscopic only)	13 (9%)	24 (29%)	0.001
Vascular necrosis	0 (0%)	1 (1%)	0.469
Inflammatory response
Chorioamnionitis (MIR)	56 (40%)	25 (30%)	0.390
Villitis (MIR)	38 (27%)	19 (23%)	1.000
Funisitis of cord (FIR)	14 (10%)	1 (1%)	0.015
Vasculitis of cord vessels (FIR)	14 (10%)	4 (5%)	0.500
Outcome
Intrauterine growth restriction	12 (9%)	25 (33%)	0.000
Low birthweight	99 (72%)	69 (85%)	0.059
Stillbirths	27 (19%)	26 (31%)	0.137
Infant demise before 1 year	10 (7%)	4 (5%)	1.000

SPTB, spontaneous preterm birth; IPTB, iatrogenic preterm birth; Bold indicates significant p-value; MIR, maternal inflammatory response; FIR, fetal inflammatory response.