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

Ayla Coussa; Thomas M Barber; Zakwan Khrait; Samer Cheaib; Hayder A Hasan

doi:10.4103/jhrs.jhrs_168_21

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

J Hum Reprod Sci. 2022 Apr-Jun;15(2):163-170. doi: 10.4103/jhrs.jhrs_168_21. Epub 2022 Jun 1.

Authors

Ayla Coussa¹, Thomas M Barber¹, Zakwan Khrait², Samer Cheaib², Hayder A Hasan³

Affiliations

¹ Division of Biomedical Sciences (T.M.B.), Warwick Medical School, University of Warwick, Clinical Sciences Research Laboratories, University Hospitals Coventry and Warwickshire, Clifford Bridge Road, Coventry, CV2 2DX, United Kingdom.
² Fakih IVF Fertility Center, Jumeirah, Dubai, United Arab Emirates.
³ Department of Clinical Nutrition & Dietetics, University of Sharjah, Muwailih, Sharjah, United Arab Emirates.

Abstract

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

Aims: 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.

Study setting and design: Retrospective cohort.

Material and methods: 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.

Statistical analysis: 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).

Results: 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.

Conclusion: 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.

Keywords: Gestational hypothyroidism; in vitro fertilisation; in vitro fertilisation-pregnancy; pregnancy; thyroid disease; thyroid-stimulating hormone.