Hypothyroidism in pregnancy is associated with miscarriage, preterm delivery, low birth weight, and irreversible cognitive deficits. The American Thyroid Association recommends a pre-conception TSH less than 2.5 mIU/L be maintained to decrease these risks. It has yet to be determined if the benefit of this recommendation is limited to optimizing the gestational environment or if it extends to the oocyte. This analysis seeks to determine if a TSH less than 2.5 mIU/L impacts oocyte quality.METHODS:
Euthyroid oocyte donors at a single center from 2002–2014 were included. Patients were divided into 2 groups: group A (TSH less than 2.5 mIU/L) or group B (TSH between 2.5 and 4.5 mIU/L). The number of oocytes retrieved, zygotes formed, and blastocysts formed was compared between groups. Analysis was performed using a student's t test.RESULTS:
493 patients had a TSH less than 2.5 mIU/L, and 83 patients had a TSH between 2.5 and 4.5 mIU/L. The mean age of patients was not different between groups (26.7±3.7 vs 26.8±4.0 years, P=.7084). The difference in the number of oocytes retrieved (15.7±7.7 vs 16.3±7.6, P=.5092), zygotes formed (14.2±7.2 vs 14.0±6.8, P=.8249), or blastocysts formed was not statistically significant (5.4±4.1 vs 5.0±4.4, P=.4258).CONCLUSION:
Hypothyroidism in pregnancy is associated with significant morbidity. While a TSH less than 2.5 mIU/L in the pre-conception period is recommended, this level does not appear to impact oocyte quality. Clinicians should maintain a TSH less than 2.5 mIU/L knowing its protective effect is likely due to optimization of the gestational environment.