Low plasma folate levels increase miscarriage rates
Low plasma folate levels increase the risk of miscarriage by about 50
per cent, according to researchers from the Karolinska Institute in Stockholm.
Furthermore, they say there is no excess risk for women with high levels
of plasma folate (JAMA 2002;288:1867).
Dr Lena George and colleagues looked at the association between levels
of plasma folate and risk of miscarriage after some earlier studies suggested
that both folic acid deficiency and use of folic acid supplements could
cause spontaneous abortion. Between 1996 and 1998 they identified 562
women who had had a spontaneous abortion and who agreed to participate
in the study. Control cases were selected from pregnant women seeking
prenatal care. Plasma folate levels were measured at the time of miscarriage
diagnosis or at interview (controls).
The researchers found that compared with women with plasma folate levels
of between 5.0 and 8.9 nmol/L, women with low folate levels (4.9nmol/L
or below) had a higher risk of spontaneous abortion (adjusted odds ratio
1.47, 95 per cent confidence interval 1.01–2.14). Women with higher
plasma folate levels (between 9.0 and 13.9nmol/L, and 14.0nmol/L or above)
showed no increased risk of spontaneous abortion (OR 0.84, 0.59–1.20
and OR 0.74, 0.47–1.16, respectively). “Given the concern that
folic acid supplements, which produce high folate levels, may increase
abortion rates, this is an important finding,” they say.
The researchers add that their results have important public health and
clinical implications. They conclude: “Countries that have fortified
their food supplies with folic acid and those considering doing so can
be reassured that fortification most likely will not increase spontaneous
abortion rates and might even decrease them.”
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