Peripheral insertion of umbilical cord.

Numerous studies have addressed the significance of marginal and membranous umbilical cord (UC) insertion. Recent reports suggest that an eccentrically inserted UC may also be important. This case-control study assessed the potential relevance of peripheral insertion of UC (PIUC), defined as <3 cm from the nearest margin. Singleton placentas (n  =  1418) submitted to the pathology department over an 18-month period were analyzed. Each case of PIUC (n  =  119) was matched with a control placenta of the same gestational age. Placentas with marginal or membranous UC and multiple gestations were excluded. The overall prevalence of PIUC was 8.4%, but PIUC frequency was significantly increased in premature births at <28 weeks (21.4%, P < 0.001). There was no association with other adverse pregnancy outcomes. PIUC was associated with decreased placental weight Z-score (-0.69 ± 0.92 versus -0.22 ± 1.3, P  =  0.0056), but not fetal weight Z-score, suggesting increased utilization of placental reserve. PIUC was also associated with relatively elongated placentas (length minus width: 2.6 ± 3.2 versus 1.0 ± 3.1, P  =  0.006). PIUC tended to be more frequent in young primiparous mothers and was significantly less common in women with a history of prior curettage (66% vs 50%, P  =  0.013). These data, together with equivalent rates of prior cesarean section, multiparity, and advanced maternal age, support a primary developmental disorder as opposed to secondary placental migration due to underlying uterine abnormalities ("trophotropism"). Except for a borderline significant association with findings suggestive of maternal malperfusion (P  =  0.078), PIUC was not associated with other placental lesions.