No male predominance in offspring of women with rheumatoid arthritis or systemic lupus erythematosus

To assess the proportion of male versus female offspring of women diagnosed with SLE or RA, disorders in which female predominance is well known and PsA a disease in which female dominance is less established. The study population encompassed all females aged 16–46, who were members of the Maccabi Health Services (MHS) throughout the period of 2000–2011 and had at least one pregnancy. Data were retrieved from the computerized database of MHS, a 2-million enrollee health maintenance organization operating in Israel. The database was also used to collect data on patients with RA, SLE, and PsA. A total of 182,073 women had at least one indication of pregnancy during the study period. Among them, 546, 270, and 170 were diagnosed with RA, SLE, and PsA, respectively. The proportion of live-born males in 380,472 offspring of women free of these diseases was 51.5 % (95 % CI 51.4–51.7 %). The proportion (95 % CIs) of male offspring born to mothers diagnosed with of RA, SLE, and PsA were 46.3 % (42.3–50.3 %), 51.8 % (46.6–57.0 %), and 50.6 % (42.8–58.5 %), respectively. Our findings support the primary contribution of the hormonal phenotype rather than the genetic phenotype on autoimmunity. Neither patients with SLE or RA differ from the general population by the sex of their offspring.