Women with RA at risk of premature birth

Researchers excluded multiple births, adoptions and children who they could not link to their mothers. Of the remaining 1,917,723 children, 2101 were born to mothers with RA diagnosed before the baby's birth. Another 11,455 children were born to women diagnosed after giving birth, which researchers called 'preclinical' RA.

Children born to mothers with RA had similar body length, and head and abdominal circumference as babies of mothers without RA. However, in mothers with RA, the baby's birth weight was, on average, 80g lower and placental weight was 13.7g lighter than in controls after adjusting for confounders including smoking. In babies born to mothers with pre-clinical RA, birth and placental weights were, on average, 50.6g and 4.7g lighter respectively, although the latter was not statistically significant. In addition, children of mothers with RA and pre-clinical RA were 48% and 32% respectively more likely to be born prematurely, which might account for the difference in size. However, any long-term health effects among children born to mothers with RA will need further investigation.