Fetal growth and preterm birth in children exposed to maternal or paternal rheumatoid arthritis: a nationwide cohort study.
OBJECTIVE
To assess indicators of fetal growth and risk of preterm birth in children of parents with rheumatoid arthritis (RA).


METHODS
Through linkage of Danish national registries, we identified all children born in Denmark between 1977 and 2008. We used general linear regression models to estimate mean differences in indicators of fetal growth among children with a parent with RA compared to unexposed children. Odds ratios (ORs) and 95% confidence intervals (95% CIs) of preterm birth were calculated using a logistic regression model.


RESULTS
Of the 1,917,723 children included, a total of 13,556 children were exposed to maternal RA or maternal preclinical RA. Children exposed to maternal RA (n = 2,101) had approximately similar length, head circumference, and abdominal circumference at birth compared with children of mothers without RA. Birth weight was 87 gm lower (mean difference -87.04 gm [95% CI -111.23, -62.84]) and placenta weight was 14 gm lower (-13.45 gm [95% CI -21.46, -5.43]) than those in children of mothers without RA. Rather similar results were found in children exposed to maternal preclinical RA (n = 11,455). Compared with unexposed children, a higher risk of preterm birth was found in children exposed to maternal RA (OR 1.48 [95% CI 1.20, 1.84]) and preclinical RA (OR 1.32 [95% CI 1.07, 1.64]). No associations were found with paternal RA.


CONCLUSIONS
Children exposed to either maternal RA or maternal preclinical RA are more often born preterm. However, indicators of fetal growth measured at birth were only slightly lower than those in unexposed children.
Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Ane L
AL
Rom
Chun S
CS
Wu
Jørn
J
Olsen
Hanne
H
Kjaergaard
Damini
D
Jawaheer
Merete L
ML
Hetland
Mogens
M
Vestergaard
Lina S
LS
Mørch
D001172:Arthritis, Rheumatoid; D001724:Birth Weight; D049628:Body Size; D016241:Child of Impaired Parents; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005220:Fathers; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D009035:Mothers; D016017:Odds Ratio; D010920:Placenta / Q000033:anatomy & histology; D011247:Pregnancy; D011248:Pregnancy Complications; D047928:Premature Birth / Q000453:epidemiology*; D012042:Registries