Preconceptional thyroid-stimulating hormone levels and outcomes of intrauterine insemination among euthyroid infertile women.

OBJECTIVE: To evaluate differences in intrauterine insemination (IUI) outcomes among euthyroid women with preconceptional thyroid-stimulating hormone (TSH) values in the normal (0.4-2.4 mIU/L) and high-normal (2.5-4.9 mIU/L) ranges.

DESIGN: Cohort study.

SETTING: A single fertility center.

PATIENT(S): A total of 1,477 women who underwent 4,064 IUI cycles between the years 2004 and 2012.

INTERVENTION(S): None.

MAIN OUTCOME MEASURE(S): Live birth, clinical pregnancy, spontaneous abortion (SAB), and IUI cycle parameters.

RESULT(S): Cycles were categorized into 4 groups based on preconceptional TSH values: 0.40-1.36 mIU/L; 1.37-1.86 mIU/L; 1.87-2.49 mIU/L; and 2.50-4.99 mIU/L. No statistically significant differences were found in IUI cycle parameters, clinical pregnancy rates, or live births per initiated cycle among the 4 TSH groups. However, preconceptional TSH was inversely related to SAB and positively related to live birth among women who achieved a clinical pregnancy. In this group of women, cycles with TSH values between 2.5 and 4.9 mIU/L were related to lower odds of SAB (odds ratio: 0.32; 95% confidence interval: 0.16-0.65) and higher odds of live birth (odds ratio: 2.80; 95% confidence interval: 1.43-5.48) compared with cycles among women in the lowest TSH group.

CONCLUSION(S): Among euthyroid patients, preconceptional TSH values in the high-normal range (between 2.5 and 4.9 mIU/L) are not associated with adverse IUI outcomes.