Anticomplementary activity in serum of women with a history of recurrent pregnancy loss

Viral complement fixation tests on women with a history of recurrent pregnancy loss were complicated by the presence of anticomplementary activity. This activity reflects the presence of a factor(s) in a patient's serum that nonspecifically fixes complement. When all patient sera tested were compared, 64.7% of women with recurrent pregnancy loss had anticomplementary activity compared with 22.0% among normal fertile pregnant women (p < 0.01). In delineating when anticomplementary activity developed, it was found that 41.8% of women with recurrent pregnancy loss compared with 12.9% of normal pregnant women had this activity on entry to the study (p < 0.01). This was primarily due to the fact that among women with recurrent pregnancy loss 50.0% of the pregnant versus 33.0% of the nonpregnant women had activity (NS). However, 55.2% of the anticomplementary negative women with recurrent pregnancy loss converted to a positive status compared with 15.4% of normal women (p < 0.05). This was directly influenced by a conversion rate of 78.6% during pregnancy among women with recurrent pregnancy loss who entered the study nonpregnant and with no known cause for loss compared with a 33.3% conversion rate in their pregnant counterparts with recurrent pregnancy loss (p < 0.025). Conversion to positive anticomplementary status occurred primarily by 20 weeks of gestation and appeared to be transient. Overall there was no association between the presence of anticomplementary activity and cervical colonization with genital mycoplasmas. The data suggest that women with a history of recurrent pregnancy loss develop a serum factor(s), usually by 20 weeks' gestation, that fixes complement. Thus these observations describe an additional anomaly in the immune system of women who experience recurrent pregnancy loss.