January 15, 2009

Smoking may affect mom/fetal thyroid

Smoking during pregnancy may impair thyroid function of both mother and fetus, British researchers said.

The study, published in the Journal of Clinical Endocrinology & Metabolism, examined thyroid hormone levels in the umbilical cord of babies born to smoking mothers and found that smoking-related changes in thyroid function extend to the fetus.

However, the researchers found that in the mothers who stopped smoking during pregnancy, thyroid hormone levels were comparable to levels found in non-smokers -- suggesting that the changes in thyroid function are rapidly reversible.

We studied the influence of cigarette smoking on thyroid function of two groups of women at different stages of pregnancy -- one in the first trimester and the other in the third trimester, study co-author Dr. Bijay Vaidya of Peninsula Medical School at Royal Devon and Exeter Hospital in Exeter, England, said in a statement. In both groups we found that smoking during pregnancy is associated with changes in the mothers' thyroid hormone levels.

Optimal maternal thyroid function during pregnancy is vital for a successful pregnancy outcome, Vaidya explained. Adverse outcomes associated with thyroid dysfunction during pregnancy include increased risk of miscarriage, premature birth, low birth weight and impaired neuropsychological development of the baby.