Maternal vascular lesions in placentae of small-for-gestational-age infants.

Placentae from 140 term pregnancies were studied. Seventy-four were from uncomplicated pregnancies in which the neonates were within the normal weight range for their gestational age. The remaining 66 placentae were from pregnancies whose infants were small for gestational age (SGA). In eight cases of this latter group a curettage of placental bed was performed during caesarean section. Maternal arterial vessels with absence of trophoblastic migration were observed in basal decidua and basal plate, and acute atherosis in parietal decidua, basal decidua and basal plate, all of them in cases of the SGA group. Furthermore, chronic vasculitis-like lesions were observed in the parietal decidua of three cases from the SGA group and in two others of the control group. No vascular lesions were found in cases of the control group when an infant's birthweight was above the 25th percentile of the normal ponderal range. Atheromatous-like lesions have been described in placental bed arteries in pre-eclampsia, systemic lupus erythematosus and SGA infants: this type of vasculopathy has also been described in rejection of renal transplants. Moreover, lesions similar to those found in chronic vasculitis were also described in the latter pathological entity. It is suggested that these vasculopathies may represent different steps of the same lesion. On the other hand, they may also be the expression of a maternal immunological attack on placental tissues causing a deficit of placentation, low birthweight being the consequence of this deficit.