A recent meta-analysis indicated strong association between thyroid auto-antibodies, and miscarriage and pre-term birth.
Miscarriage (the loss of a pregnancy before 24 weeks of gestation) and pre-term birth (delivery of a baby between 24 and 37 completed weeks of gestation) are the two most common complications of pregnancy.
In a systemic review, Dr. Shakila Thangaratinam of Birmingham Women's Hospital, United Kingdom and colleagues evaluated the link between thyroid auto-antibodies, miscarriage and pre-term birth in women with normal thyroid function.
Study reports indicated the results of 30 articles with 31 studies (19 cohorts and 12 case-controls) which involved 12,126 women and assessed the association between thyroid auto-antibodies and miscarriage. The association with pre-term birth was evaluated in five studies involving 12,566 women. Out of the 31 studies evaluating miscarriage, 28 showed a positive association between thyroid auto-antibodies and miscarriages.
Meta-analysis of the cohort studies showed a three-fold increase in the odds of miscarriage with the presence of thyroid auto-antibodies. For case-control studies the odds ratio for miscarriage was 1.80, 1.25 to 2.60; P = 0.002. There was a significant rise in the odds of pre-term birth with the presence of thyroid.
Two other randomized studies evaluated the effect of treatment with levothyroxine on miscarriage. Both showed a decline in the rate of miscarriage and the meta-analysis showed a 52 percent relative risk reduction in miscarriages with the use of levothyroxine.
The authors concluded the study by reporting that the presence of maternal thyroid auto-antibodies is strongly associated with miscarriage and pre-term delivery. Also, there is evidence that treatment with levothyroxine can diminish adverse outcomes of pregnancy.