Intrauterine growth retardation of unknown etiology: II. Serum complement and circulating immune complexes in maternal sera and their relationship with parity and chronic villitis.

Significantly lower CH50 levels were found in women with small for gestational age (SGA) infants. The lowest values corresponded to nulliparous with placental chronic villitis (124.0 +/- 10.6). Three out of five mothers with circulating immune complexes from SGA group were nulliparous, having placental chronic villitis. An immunological derangement in women with SGA infants is proposed for the development of placental lesions, mainly in nulliparous mothers with a lower previous exposure to fetal antigens.