Oocyte donation (OD) is a specific method of artificial reproductive technology that is accompanied by a higher risk of
preeclampsia during pregnancy. The pathophysiological mechanism underlying
preeclampsia in OD pregnancies is thought to differ from
preeclampsia in autologous pregnancies. As
preeclampsia in autologous pregnancies is suggested to be associated with complement activation, we studied C4d deposition, circulating
complement components and placental
complement regulatory
proteins in preeclamptic OD pregnancies. Women with uncomplicated and preeclamptic pregnancies after OD or spontaneous conception were selected. We stained the placentas for C4d, marker for complement activation, measured
complement factors C1q, C3 and C4 in maternal sera and quantified the placental
mRNA expression of
complement regulatory
proteins CD46, CD55 and CD59. A significantly (p < 0.03) higher incidence of C4d deposition was observed in placentas from women with
preeclampsia compared with uncomplicated pregnancies, both OD and autologous. The level of
complement factors in serum did not differ between the groups. Children born in the autologous
preeclampsia group were significantly lower in
birth weight (p < 10th percentile) compared with the preeclamptic OD group. In addition, the placental
mRNA expression level of
complement regulatory
proteins was significantly lower in uncomplicated and preeclamptic OD compared with the autologous pregnancies. In line with autologous
preeclampsia pregnancies, there is excessive activation of
complement in preeclamptic OD pregnancies. However, in contrast to autologous pregnancies this is not associated with counterbalancing upregulation of
complement regulatory
proteins. Furthermore, C4d deposition in OD pregnancies is not related to the severity of
preeclampsia, suggesting another trigger or regulatory mechanism of placental C4d deposition in preeclamptic OD pregnancies.