Impact of Vitamin D Level on Early Pregnancy Outcomes in Obese Patients Following Intrauterine Insemination

Abstract

autoimmunity is a known cause of hypothyroidism. Overt hypothyroidism is an established cause of recurrent pregnancy loss (RPL) that is effectively treated with levothyroxine (LT).As it is unclear how thyroperoxidase antibody (TPOAb) positivity impacts thyroid stimulating hormone (TSH) levels during subsequent pregnancies, the primary objective of this study was to examine the TSH levels for RPL patients during pregnancies following the index visit.A preliminary analysis was performed to ascertain if subclinical hypothyroidism can be treated with LT to improve live birth rate (LBR), LBR in borderline subclinical hypothyroidism (B-SCH) (TSH 2.5-4 mIU/L) and clinical/subclinical hypothyroidism (C/SCH) (TSH > 4 mIU/L) with and without LT was compared to euthyroid patients (TSH 0.1-2.5 mIU/L).MATERIALS AND METHODS: A retrospective chart review of 1444 RPL patients seen at the BC Women's Hospital was conducted. 828 euthyroid patients, 269 B-SCH (116 treated, 153 untreated), and 103 C/SCH (65 treated, 38 untreated) were included. TSH in pregnancies after the initial visit across TPOAb status was analyzed using mixed-effects linear regression. Across euthyroid, B-SCH, or C/SCH patients, LBR was analyzed using Poisson regression.RESULTS: The baseline characteristics showed no significant difference in age, body mass index, or number of previous live births or pregnancy losses between euthyroid, B-SCH, or C/SCH groups. The distribution of RPL causes between groups revealed no difference in genetic or anatomic causes but a higher rate of hyperprolactinemia (p¼0.003) and anti-phospholipid antibody syndrome (APS; p¼0.026) in those with C/SCH. Analysis of TSH showed no significant change across TPOAb or treatment status (p¼0.24) for up to four subsequent pregnancies. An increased LBR in B-SCH when treated with LT relative to untreated B-SCH (OR¼ 1.67, p¼0.0037) was seen. In C/SCH patients, there was no significant change in LBR when treated with LT relative to untreated C/SCH patients (OR¼1.52, p¼0.17).CONCLUSIONS: In the RPL population, TPOAb positivity is not correlated with change in TSH levels over time. RPL patients with C/SCH are more likely to have hyperprolactinaemia and APS.IMPACT STATEMENT: This research provides evidence for how TSH levels change following the index visit in the RPL population.