Effects Of Subclinical Hypothyroidism On The Clinical Outcomes Of Assisted Reproduction Techniques

Objective:To investigate the effects of subclinical hypothyroidism(SCH)on the clinical outcomes during in vitro fertilization and embryo transfer(IVF/ICSI-ET).And to establish the reference range of thyroid hormone for infertile women in our hospital.The study were intended to reduce the rate missed diagnosis and misdiagnosis rates and improve the outcome of pregnancy.Methods:The study was compartmentalized into the following two parts.1.The data of patients undergoing IVF/ICSI-ET from January 2017 to Decemberr2018 in the Reproductive Medical Center of the Affiliated Hospital of Qingdao University was analyzed retrospectively.The patients were put into different groups based on different thyroid stimulating hormone(TSH).The influence of SCH on the clinical outcomes was aimed to research.2.The data were retrospectively collected from infertile women with examination in the Reproductive Medical Center of the Affiliated Hospital of Qingdao University from January 2018 to December 2019.3,074 cases of infertile women who participated the study were selected as the "standard population" and grouped by age.The levels of TSH,free thyroxine(FT4)and Free triiodothyronine(FT3)were measured.The inspecting values were used to establish the reference range of each specific thyroid function parameter.Subsequently,1,089 cases of infertile women were collected to validate whether the reference range complies with the standard of diagnosing SCH.The method to validate was comparing to the diagnostic criteria as proposed by Chinese Society for Reproductive Medicine Consensus for subclinical hypothyroidism in the infertile female population in 2018.Result:1.The conclusion drawn from the laboratory parameters is that the number of retrieved oocytes,the fertilization rate,high quality embryo rate and the quatity of transplantable embryo among the groups showed no significant difference(P>0.05).But high quality embryo rate reduced as the TSH rised.2.We can draw a conclusion from the data of the outcome of pregnancy.The clinical pregnancy rate,miscarriage rate and live birth rate were no significantly different(P>0.05)among the groups.With the increasing of TSH,biochemical pregnancy rate was on the rise;and biochemical pregnancy rate had statistical difference(P<0.05).And biochemical pregnancy rate was significant higher in 3.8<TSH≤4.5 group.3.We can come to the conclusion from the laboratory parameters.The comparison of the data which was above and below the cut-off value in different TSH cut-off values showed that there was no statistically significant difference in the number of retrieved oocytes,the fertilization rate,the quatity of transplantable embryo and high quality embryo rate(P> 0.05).However,when the TSH cut-off values were 1.0 m IU/L,1.7m IU/L,2.4 m IU/L,3.1m IU/L,and 3.8 m IU/L,the high quality embryo rate was not statistically different.Although the difference was no statistically significant,the high quality embryo rate was relatively higher in the group which was below the cut-off valuet.4.It can be concluded from the data of the outcome of pregnancy.The comparison of the data which was above and below the cut-off value in different TSH cut-off values showed that biochemical pregnancy was higher in the group which exceeded the cut-off value.When the TSH cut-off values were 2.4 m IU/L,3.1 m IU/L and 3.8 m IU/L,the difference of the biochemical pregnancy rate was statistically significant.The biochemical pregnancy rate increased as TSH cut-off values increased;and the gap between the groups increased gradually.Clinical pregnancy rate,miscarriage rate and live birth rate between the groups had no differences in statistics(P> 0.05).But the miscarriage rate in the high TSH group was higher.5.In the group of infertile women under 30 years old,the reference ranges of serum TSH were 0.26-3.81 m IU/ml,3.64-5.71 pmol/L for FT3 and 11.18-20.8 pmol/L for FT4.In the group of infertile women between 30 and 40 years old,the reference ranges of serum TSH were 0.14-3.94 m IU/ml,3.32-5.68 pmol/L for FT3 and 9.17-18.49 pmol/L for FT4.And in the group of infertile women over 40 years old,the reference ranges of serum TSH were 0.64-4.42 m IU/ml,3.04-5.1 pmol/L for FT3 and 8.53-18.99 pmol/L for FT4.6.Diagnoses were made according to the reference standard as proposed by Chinese Society for Reproductive Medicine consensus for subclinical hypothyroidism in the infertile female population in 2018 and the reference range of values established in this study.The overall prevalence of SCH was 5.42%(59/1089)and 1.93%(21/1089)respectively.After testing,the prevalence in the group of reference values was higher than that in the group of consensus recommendation(5.91%>1.48%,4.80%>1.95%,8.70%>2.61%),there were no demographic differences(P<0.05).Conclusion:1.The biochemical pregnancy rate is significantly higher in SCH patients undergoing IVF/ICSI-ET.In the groups of SCH patients,high quality embryo rate shows a downward trend and miscarriage rate is on the increase.Therefore,it is necessary to pay more attention to the process of IVF/ICSI-ET and thyroid function during pregnancy of patients with subclinical hypothyroidism to prevent the occurrence of adverse pregnancy outcomes.2.The serum thyroid hormone in different age groups of infertile women is very different.The reference ranges of thyroid hormone in different age groups cannot be substituted mutually.3.Using the reference range of values recommended by the consensus to interpret the thyroid function of infertile women in our hospital may lead to misdiagnosis,which could result in excessive clinical intervention.Therefore,the establishment of this reference range provides an important basis for establishing the standard of diagnosing for infertile woman in our hospital.