Our aims were to assess the frequency of false-positive IgM antibodies for cytomegalovirus in pregnant women with autoimmune diseases and in healthy women (controls) and to determine their relationship with pregnancy outcome. Data from 265 pregnancies in 236 patients with autoimmune diseases and from 265 pregnancies in 243 controls were assessed. When positive IgM for cytomegalovirus was detected, IgG avidity, cytomegalovirus isolation and polymerase chain reaction for CMV-DNA in maternal urine, blood and amniotic fluid samples were performed in order to identify primary infection or false positivity. A statistically significantly higher rate of false-positive IgM was found in pregnancies with autoimmune diseases (10%) in comparison with controls (0.7%). A worse pregnancy outcome was observed among patients with autoimmune disease and false cytomegalovirus IgM in comparison with those without false positivity: earlier week of delivery (p < 0.0001), lower neonatal birth weight (p < 0.0001) and neonatal birth weight percentile (p < 0.0001), higher rate of intrauterine growth restriction (p = 0.004) and babies weighing less than 2000 g (p < 0.0001) were encountered. The presence of false cytomegalovirus IgM in patients with autoimmune diseases could be used as a novel prognostic index of poor pregnancy outcome: it may reflect a non-specific activation of the immune system that could negatively affect pregnancy outcome.
- Pregnancy outcome
- False-Positive Igm for Cmv