Relationship between Maternal Serum Thyroid-Stimulating Hormone and in vitro Fertilisation-Conceived Pregnancy...

Thyroid dysfunction impairs female fertility and pregnancy outcome. Optimal preconception and gestational TSH level is still debatable in IVF-conceived pregnancies.

To explore the relationships of IVF success and pregnancy outcomes with maternal serum levels of TSH (at both preconception and 12-week IVF-conceived pregnancy). Also, to confirm or refute the recommended TSH level ≤2.5μIU/mL.

Retrospective cohort.

158 IVF-conceived pregnant women and 117 age-matched controls non-pregnant (≤39years, BMI 18.5-38kg/m2) were recruited. Preconception and 12-week IVF-conceived pregnancy serum samples were analysed for reproductive hormones, fasting glucose, insulin and TSH levels. Data of pregnant women at 28 weeks for GDM screening (75-gram OGTT) and up until delivery were included.

Binary logistic regression used to predict association between preconception TSH levels and IVF success, and pregnancy outcomes. Association of delta change of hormones was determined with linear regression. Significance level P≤0.05 with 95% confidence interval (CI).

Overall, median (IQR) age was 32(6)years, BMI 25.4(6.9)kg/m2, HbA1c 5.2(0.52)% and TSH 1.82(1.4)μIU/mL. There was no significant association between preconception TSH level and IVF success rate. During the first trimester of IVF-conceived pregnancy, delta change in TSH level was associated with that of progesterone (P=0.03). 12-week gestation TSH level did not predict adverse pregnancy outcomes (i.e. onset of GDM, delivery type and premature delivery); but a higher TSH level predicted earlier delivery in weeks. There was a higher risk of delivery by caesarean section when TSH>2.5μIU/mL.

Variation of maternal TSH within normal range (0.4-4.0μIU/mL) at preconception and 12-week gestation has no predictive effect on IVF success and pregnancy outcomes in IVF-pregnancy. Our data provide no support for a recommended preconception TSH level ≤2.5μIU/mL in IVF-conceived pregnancy, but rather promote a preconception TSH level within normal range.