Maternal thyroid function in women undergoing controlled ovarian hyperstimulation during in-vitro fertilization and...

We conducted a study to evaluate the changes in thyroid function during controlled ovarian hyperstimulation (COH) and its association with the outcome of assisted reproductive technique (ART).

This is a prospective cohort study done in University Hospital Fertility Clinic for one year duration. A total of 88 euthyroid women who underwent COH as part of planned in-vitro fertilization (IVF) were invited to participate in this study. Serum thyroid function of each women will be monitored before stimulation (T1), day 10-13 of cycle (T2), during oocyte retrieval (T3), one week following embryo transfer (T4), and at four weeks after embryo transfer (T5). Reproductive outcome of IVF will be observed and documented.

Nine women had ongoing singleton pregnancy, seven suffered from miscarriage, while the rest had implantation failure. Serum thyroid-stimulating hormone (TSH) and free thyroxine (fT4) increased throughout stimulation, peaking at 32-36 hours after hCG administration compared to baseline (1.250 vs. 1.740 mIU/L and 13.94 vs. 15.25 pmol/L). It remains elevated until one week following embryo transfer. The increment of serum TSH exceeded the upper limit, acceptable for first trimester (<1.60 mIU/L). However, the evolution of serum TSH and fT4 did not significantly differ with pregnancy outcome.

In euthyroid women, thyroid function changed significantly during COH, but these changes were not different between the three reproductive outcomes. Thus, we do not suggest continuous thyroid function monitoring during COH.