Obstetric outcomes in thyroid cancer survivors: A retrospective cohort study

Objective To investigate whether thyroid cancer survivors would have increased risks of adverse obstetric outcomes. Methods Data from 154 women with a history of thyroid cancer who had a live birth at Peking University Third Hospital from January 2012 to December 2019 were collected. The control group consisted of 308 women without any thyroid disease or malignant tumor. Age and year of delivery were matched between the two groups. Results Serum levels of thyroid stimulating hormone and free thyroxine were significantly lower and higher in thyroid cancer patients, respectively (P < 0.001). After adjusting for age, pre-pregnancy body mass index, pre-pregnancy hypertension, pre-pregnancy diabetes mellitus, previous cesarean section, and conception by in vitro fertilization/intracytoplasmic injection, adverse obstetric outcomes including preterm birth (odds ratio [OR] 0.73, 95% confidence interval [CI] 0.32-1.67), low birth weight infant (OR 1.05, 95% CI 0.44-2.50), gestational diabetes mellitus (OR 0.86, 95% CI 0.54-1.39), and pre-eclampsia (OR 1.11, 95% CI 0.34-3.57) showed no differences between thyroid cancer survivors and the control group. However, pregnant women with a history of thyroid cancer had a higher risk of abnormally invasive placentation (OR 10.57, 95% CI 1.22-91.97, P = 0.032). Conclusion Although the thyroid function status of thyroid cancer patients was different from that of pregnant women without any thyroid disease or malignancy, they would not be at a higher risk of most adverse obstetric outcomes except for abnormally invasive placentation.