Secondhand tobacco smoke exposure is associated with prolactin but not thyroid stimulating hormone among nonsmoking women seeking in vitro fertilization.

Prolactin (PRL) and thyroid stimulating hormone (TSH) serve important roles in the reproductive and other systems. Active smoking is associated with changes in PRL and TSH secretion, but the relationship between secondhand tobacco smoke (STS) exposure and these hormones is unclear. We measured PRL and TSH in serum as well as cotinine in follicular fluid (to estimate STS exposure) among 314 nonsmoking women undergoing in vitro fertilization treatment. We observed a significant increase in PRL concentrations (p=0.03) among STS-exposed nonsmokers compared to unexposed nonsmokers. There was no significant difference in TSH concentration (p>0.4) among those exposed to STS compared to those who were unexposed. STS exposure is associated with an increase in circulating PRL but not TSH levels. Future studies are needed to confirm our results, identify biological mechanisms involved, and better understand the potential clinical and public health implications.