Dr Taylor explains: "Borderline thyroid function in pregnant women can cause problems for the unborn child. However it remains unclear whether screening during pregnancy and treating borderline hypothyroidism with levothyroxine improves outcomes. This is an important issue to address as potentially substantial benefits might be achieved including reducing the risk of miscarriages and premature delivery.
"It is particularly challenging to conduct trials of this nature in pregnancy; however we studied a large previously conducted trial - the Controlled Antenatal Thyroid Study (CATS). This measured thyroid function at the end of the first trimester and treated women with borderline thyroid hormone levels with levothyroxine to see if that improved neurological development in offspring. Using advanced data linkage methods we were able to electronically capture key pregnancy outcomes. As a result we had effectively a free trial of thyroid hormone screening and treatment in pregnancy.
"Our results were supportive of undertaking thyroid screening in pregnancy as we established a link between sub-optimal maternal thyroid function and adverse pregnancy outcomes. Furthermore we also showed that levothyroxine treatment improved birth-weight and reduced the risk of premature delivery and also may have some protective impact on stillbirths and the number of emergency caesarean sections needed."