Increased Miscarriage Rate with PCOS
Is the miscarriage rate higher in women with PCOS?
There does appear to be a higher miscarriage rate in women with PCOS, but the exact
reason is still under investigation. According to some studies, the risk of miscarriage
in women with PCOS is 45 percent or more. One possibility is that early loss is
associated with elevated levels of luteinizing hormone and women with PCOS often have
elevated LH levels but the reason why it relates to miscarriage is not understood.
Another possibility is that elevated levels of insulin or glucose may impede implantation
or cause problems with the embryonic development. There is a clear association between
uncontrolled blood sugar and pregnancy loss, but the issue of insulin resistance and
elevated insulin levels is relatively new and in need of further study. There is a
possibility that insulin resistance reduces egg quality. That leads to another possibility
that late ovulation (after cycle day 16) may be associated with poor follicle
development and decreased egg quality.
Is there anything that can be done to reduce the chance of miscarriage in a woman with PCOS?
The primary way to reduce miscarriage associated with PCOS is to normalize hormone levels.
For women with low progesterone levels in the luteal phase, improving ovulation through
the use of clomiphene citrate, or injectable FSH or FSH/LH may help the problem. Addressing
ovulation issues is more useful than progesterone supplementation as low progesterone is
usually a symptom of a problem, such a weak ovulation, rather than the actual cause of
miscarriage. Normalizing blood sugar and glucose levels may help, and lead to lower androgen
levels, so use of metformin (see next question) during pregnancy is increasing. Most
doctors would have patients discontinue use of the glitazones.
Can metformin reduce the chance of miscarriage?
It appears that continuing metformin use at least through early pregnancy may reduce the
chance of miscarriage, especially in patients with recurrent losses. A recent abstract,
"Metformin throughout pregnancy in women with polycystic ovary syndrome reduces first-
trimester miscarriage" (CJ Glueck et al, J Invest Med 2000), revealed a group's experience
with 59 pregnant PCOS women. Of these, 23 were kept on metformin for the long haul. The
other 36 did not continue metformin in pregnancy. This is a very small sample, but the
miscarriage rate was 45 percent without metformin and only nine percent with metformin.
Chi-square testing showed these rates to be highly significant from a statistical point
of view, but their true clinical impact must await further prospective studies. As with any
medication used in pregnancy, doctor and patient must assess whether the benefit outweighs
any potential risk.
