title: IgA deficiency, autoimmunity & pregnancy: a population-based matched cohort study.
abstract: BACKGROUND
  Several autoimmune disorders have been linked to adverse pregnancy outcome. IgA deficiency shares many autoimmune traits, but its association with pregnancy outcome is unknown.
  
  
  METHODS
  Prospective population-based cohort study in Sweden of 613 mothers with IgA deficiency (IgA levels < .07 g/L) diagnosed in 1980-2010 in six university hospitals. In 1973-2010, these women delivered 1,172 singleton infants registered in the Swedish Medical Birth Register. Each delivery to a woman with IgA deficiency was matched on maternal age, parity, early pregnancy smoking status, education level, and delivery year with up to 5 control births (n = 5,758).
  
  
  RESULTS
  Offspring to women with IgA deficiency had 79 g lower birth weight than controls (mean ± SD: 3,457 ± 559 vs 3,537 ± 553 g, P < 0.001), and 1.4 days shorter gestational age (mean ± SD: 278 ± 13 vs 280 ± 14 days, P = 0.001). No difference in preterm birth (<37 weeks) could be detected in deliveries to women with IgA deficiency vs control deliveries (5.8 % vs 5.2 %; odds ratio (OR) = 1.13, 95%CI = 0.85-1.49), but small for gestational age birth was more common (4.3 % vs 2.8 %; OR = 1.48, 95%CI = 1.04-2.10). Women with IgA deficiency also delivered more often by caesarean section (16.9 % vs 11.9 %; OR = 1.51, 95%CI = 1.26-1.82), while no difference was observed regarding low Apgar score (<7 at 5 min; 1.1 % vs 1.0 %; OR = 1.18; 95%CI = 0.62-2.27). When excluding women with autoimmune diseases, the excess risks of adverse pregnancy outcome diminished.
  
  
  CONCLUSIONS
  There is a small excess risk of certain adverse delivery and perinatal outcomes among offspring to women with IgA deficiency. These excess risks are attenuated when considering the presence of autoimmune diseases.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden, jonasludvigsson@yahoo.com.
authors.forename: Jonas F
authors.initials: JF
authors.lastname: Ludvigsson
authors.forename: Martin
authors.initials: M
authors.lastname: Neovius
authors.forename: Olof
authors.initials: O
authors.lastname: Stephansson
authors.forename: Lennart
authors.initials: L
authors.lastname: Hammarström
mesh_terms: D000293:Adolescent; D000328:Adult; D001327:Autoimmune Diseases / Q000453:epidemiology*; D001724:Birth Weight; D002585:Cesarean Section / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D017098:IgA Deficiency / Q000453:epidemiology*; D007231:Infant, Newborn; D044382:Population Groups; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D011446:Prospective Studies; D012306:Risk; D013548:Sweden; D055815:Young Adult