The effect of I-131 therapy on pregnancy outcomes after thyroidectomy in patients with differentiated thyroid carcinoma: a meta-analysis

Purpose Studies on the effects of I-131 therapy on pregnancy outcomes after differentiated thyroid carcinoma (DTC) surgery showed inconsistent findings. The purpose of the study was to investigate the association between I-131 therapy and pregnancy outcomes in female DTC patients. Methods PubMed, Embase, Cochrane Library, CNKI, and VIP were searched until November, 2020. Keywords included differentiated thyroid cancer, thyroid carcinoma, thyroid neoplasm, radioiodine, I-131, I-131, pregnancy outcomes, reproduction, fertility, abortion, preterm birth, and congenital malformation. Studies that provided the pregnancy outcomes in DTC patients who received I-131 therapy and those who did not receive I-131 therapy were included. Meta-analysis was performed in Stata/SE 12. A random or fixed effects model was adopted according to the result of heterogeneity test. Results Seven observational studies were eligible, involving 125,591 participants and 13,811 pregnancies. It showed that postoperative I-131 therapy for DTC had no significant effect on spontaneous abortion (OR = 1.05, P = 0.701), induced abortion (OR = 1.06, P = 0.859), abortion (OR = 1.07, P = 0.098), premature birth (OR = 1.02, P = 0.756), stillbirth (OR = 1.58, P = 0.364), and congenital malformation(OR = 1.00, P = 0.986). Cumulative RAI dose >3.7 GBq or <3.7 GBq had no significant effect on abortion (OR = 0.94, P = 0.252) and congenital malformation (OR = 1.05, P = 0.752).The group in which interval time between last I-131 therapy and pregnancy >1 year had significant lower risk of abortion than with interval <1 year (OR = 0.60, P = 0.000). Conclusions Pregnancy is not recommended for DTC patients within 1 year after I-131 therapy.