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 having a parent with RA
compared to unexposed children. Odds ratios of preterm birth were calculated by 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 (2,101) had
approximately similar length, head and abdominal circumference at birth, compared with
children of mothers without RA. Birth weight was 87 gram lower (−87.04 g;
95% CI, −111.23; −62.84) and placenta weight was 14 gram lower
(−13.45 g; 95% CI, −21.46; −5.43). Rather similar
results were found in children exposed to maternal preclinical RA (11,455). Compared
with unexposed children a higher risk of preterm birth was found in children exposed to
maternal RA and maternal preclinical RA respectively (OR, 1.48; 95% CI,1.20;1.84
and OR, 1.32; 95% CI,1.07;1.64). No associations were found with paternal
RA.
Conclusion
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 in unexposed children.