Females With High Birth Weight More Likely To Develop Rheumatoid Arthritis

A new study published in the Annals of the Rheumatic Diseases
finds that compared to females born with average birth weight, those
born with heavy birth weight are two times as likely to develop
rheumatoid arthritis when they become adults. Rheumatoid arthritis is a
condition that occurs when the immune system attacks the joints, lungs
or skin and results in inflammation, pain, and loss of functioning
mobility.



Researcher L A Mandl (Division of Rheumatology, Hospital for Special
Surgery, Weill Cornell Medical College) and colleagues argue that these
findings support the fetal origin of disease theory. That is, factors
that occur during pregnancy program an individual to be more prone to
certain diseases and conditions in adult life. For example, previous
research has linked low birth weight to conditions such as diabetes,
coronary heart disease, and high blood pressure, and high birth weight
has been associated with an increased risk of breast cancer and
leukemia.



These new findings on rheumatoid arthritis development come
from a survey of more than 87,000 women, age 30 to 55, who took part in
the US Nurses' Health Study from 1976 and 2002. In two year intervals,
the women responded to questions about their health, lifestyle, and
family illness. In 1992, researchers asked them questions about birth
weight.



Between 1976 and 2002, 619 women received their first
diagnosis of rheumatoid arthritis. The average birth weight was between
3.2 to 3.85 kg, and women who weighed over 4.45 kg at birth were found
to be twice as likely to develop the autoimmune disease known as
rheumatoid arthritis. These findings held after the researchers
statistically controlled for factors that may influence birth weight
such as socioeconomic status, parental smoking, maternal diabetes, age
at first period, use of oral contraceptives or hormone replacement
therapy, breastfeeding and weight.



Though the authors do not have a clear biological explanation for their
results, they do note that abnormal hormone regulation - a process
thought to affect a baby while in the womb - is prevalent in adults
with rheumatoid arthritis.



The authors conclude that: "The biology underlying this association is
speculative, and the relative importance of fetal nutrition versus
genotype is unknown. However, if fetal nutrition has an impact on
future risk of RA [rheumatoid arthritis], this could be a potentially
modifiable risk factor. Further study of our observation that high
birth weight is associated with an increased risk of RA could provide
insight into the pathogenesis of RA. These data also provide further
evidence for the importance of fetal environment as a crucible for
future adult diseases."



Is birthweight associated with risk of rheumatoid arthritis?
Data from a large cohort study

L A Mandl, K H Costenbader, J F Simard, E W Karlson

Annals of the Rheumatic Diseases (2008).

doi 10.1136/ard.2007.080937]

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Written by: Peter M Crosta