Thyroid dysfunction in Iranian pregnant women: a systematic review and meta-analysis

Prevalence, risk factors, and consequences of hypothyroidism among pregnant women in the health region of Lleida: A cohort study

BACKGROUND

Primary maternal hypothyroidism is defined as the increase of TSH levels in serum during pregnancy. Hypothyroidism in pregnancy is the second most common endocrine disease, after diabetes mellitus, with a prevalence ranging between 3.2 and 5.5%. Its variability depends on ethnical differences. Hypothyroidism in pregnancy is associated with other chronic diseases and fetal and maternal outcomes.

OBJECTIVE

To analyze the prevalence of hypothyroidism among multiethnic pregnant women, and to evaluate the comorbidity with chronic diseases and outcomes leaded during pregnancy and newborn.

METHODS

Retrospective observational cohort study in pregnant women during the years 2012-2018 in the health region of Lleida. The relationship of hypothyroidism with different variables was analyzed by calculating the adjusted odds ratio (aOR) and the 95% confidence intervals (CI) with multivariate logistic regression models.

RESULTS

We analyzed a sample of 17177 pregnant women, which represents more than 92% of the total of pregnant women in the health region of Lleida. The annual prevalence of hypothyroidism was 5.7-7.1%. According to the region of origin, the lowest prevalence was found in the population from Sub Saharian Africa (2.1%), while the highest was from Asia and the Middle East (8.6%). Other factors associated with hypothyroidism were age, hypertension, diabetes mellitus, and dyslipidemia. In addition, we did not observe an effect of hypothyroidism on the course of pregnancy, childbirth, and on the newborn. Finally, there was a good control of the disease during pregnancy.

CONCLUSIONS

The prevalence of hypothyroidism in pregnancy was 6,5% in this study which depends on the country of origin, lower values were found in Sub Saharian African women and higher in those from Asia and the Middle East. Hypothyroidism was associated with age, diabetes mellitus, arterial hypertension, or dyslipidemia, and was not related to the Apgar score or the weight of the newborn.

A Bayesian model to estimate the cutoff value of TSH for management of preterm birth

BACKGROUND

Determining a thyroid hormone cutoff value in pregnancy is challenging issue and several approaches have been introduced to optimize a utility function. We aimed to estimate the cutoff value of TSH using Bayesian method for prediction of preterm-birth.

METHODS

This study was a secondary-analysis of the population-based data collected prospectively within the framework of the Tehran Thyroid and Pregnancy Study. A total of 1,538 pregnant women attending prenatal clinics.

RESULTS

Using Bayesian method resulted a TSH-cutoff of (3.97mIU/L,95%CI:3.95-4.00) for distinguishing pregnant women at risk of preterm-birth. The cutoff was associated with acceptable positive predictive and negative predictive values (0.84,95% CI:0.80-0.88) and 0.92 (95%CI: 0.91-0.94), respectively). In women who were negative for thyroid peroxides antibody (TPOAb) with sufficient urinary iodine concentration (UIC), the TSH cutoff of 3.92 mIU/L(95%CI:3.70-4) had the highest predictive value; whereas in TPOAb positive women with insufficient UIC, the cutoff of 4.0 mIU/L(95%:CI 3.94-4) could better predict preterm birth. Cutoffs estimated in this study are close to the revised TSH value of 4.0mIU/L which is currently recommended by the American Thyroid Association.

CONCLUSION

Regardless of TPOAb status or iodine insufficiency, risk of preterm labor is increased in pregnant women with TSH value of > 3.92 mIU/L; these women may benefit from Levothyroxine (LT4) therapy for preventing preterm birth.

Mycobacterium avium subsp. paratuberculosis and Hashimoto’s thyroiditis: Is MAP the trigger?

Hashimoto’s thyroiditis (HT) is an autoimmune disorder of the thyroid gland that can cause hypothyroidism. As HT is a multifactorial disorder, activation of immune responses in genetically predisposed individuals exposed to some environmental factors can contribute to it. Microorganisms, as environmental factors, including Mycobacterium avium ssp. paratuberculosis (MAP) by molecular mimicry, can be important in this autoimmune disorder. This study aimed to investigate the association between MAP and HT. This case–control study included 110 participants consisting of 60 HT patients and 50 healthy controls (HCs). Blood samples were collected. Nested PCR of the IS900 gene determined the presence of MAP DNA. The enzyme-linked immunosorbent assay (ELISA) was designed to identify antibodies (Abs) against the MAP3865c epitope, which has a homologous sequence with ZnT8 in the sera. The demographic information of all participants was recorded. Anti-TG, anti-TPO, TSH, anemia, and ruminant exposure were higer in HT patients than in the HCs (p < 0.05). MAP IS900 was detected significantly more in the patients (46.6% consisting of 30, 8.3, and 8.3% in clinical, subclinical, and unknown) than in the HCs (14%). The sera showed a remarkable frequency of reactivity against MAP3865c in the patients (38.3%) in comparison to the HCs (10%) (p = 0.0001). Furthermore, a significantly higher rate of livestock contact and traditional dairy consumption was found in individuals with MAP or anti-MAP3865c Abs positive result (p < 0.05). This study suggests a possible link between MAP and HT. These findings indicated that MAP frequency was not statistically different in the severity of HT and its shift into the clinical and subclinical forms; therefore, it could be assumed that MAPs are the initiators of the process. The results imply on a possible zoonosis transmission route of MAP from livestock products to humans. Further research is needed to confirm these results in larger groups of HT patients.

Short-Term Adverse Pregnancy Outcomes in Women with Subclinical Hypothyroidism: A Comparative Approach of Iranian and American Guidelines

Introduction

Subclinical hypothyroidism during pregnancy can be associated with numerous adverse outcomes. The purpose of this study was to compare short-term adverse pregnancy outcomes in treated versus nontreated patients who fall within the numerical range of thyroid-stimulating hormone (TSH) between the Iranian and American reference ranges.

Materials and Methods

Eighty pregnant women with a known level of antithyroid peroxidase (anti-TPO) and TSH levels of 2.5–3.9 mIu/L in the first trimester and 3–4.1 mIu/L in the second and third trimesters were enrolled in the study and randomly assigned into two groups including 41 patients in the intervention group and 39 in the control group. The intervention group was treated with levothyroxine at least 50 μg/day and the control group received no treatment. The data were analyzed by SPSS software version 23.

Results

The only significant findings were a correlation between pregnancy loss frequency (p − 0.011) and/or increased TSH level in the follow-up period (p = 0.008) with anti-TPO antibody positivity. Forty-four percent of mothers with positive anti-TPO Ab needed treatment initiation with levothyroxine, based on Iranian guidelines, due to increased TSH level during the follow-up period.

Conclusion

Untreated pregnant women with subclinical hypothyroidism, who were placed in the intermediate range of TSH, recommended by Iranian and American guidelines, did not show any significant difference in short-term adverse pregnancy outcomes compared to the treated patients. Positive anti-TPO Ab may play a role in the development of short-term complications in mothers with subclinical hypothyroidism or it may increase the likelihood of an increase in TSH level during pregnancy.

Adherence to treatment for hypothyroidism in pregnancy and relationship with thyrotropin control: a retrospective observational cohort study

Background

Hypothyroidism is the second most common endocrinological disease during pregnancy, with percentages that can range between 3.2 and 5.5%. A good maternal and foetal health outcome depends on thyroid hormone replacement therapy. The goal of such therapy is to maintain thyrotropin (TSH) in a range that is specific for pregnant women and varies between the trimesters of pregnancy. In our study, we wanted to analyse the adherence to hypothyroidism treatment among pregnant women and to evaluate the degree of control of the disease.

Methods

We performed a retrospective observational cohort study in pregnant women between 2012 and 2018 in the Lleida health region. Therapeutic adherence was analysed by the proportion of days covered (PDC). The relationship with other variables was assessed using the regression coefficients and their 95% confidence interval (CI).

Results

We examined a sample of 17,281 women, representing more than 92% of the pregnant women in the Lleida health region in the period analysed. Among this sample, the mean prevalence of hypothyroidism was 6.52% (0.07% clinical and 6.45% subclinical). 3.3% of the 17,281 pregnant women were treated. Among them, the mean adherence score was 79.6 ± 22.2. Of these, 54% presented high adherence. The latter had a higher mean age and better TSH control, in comparison to the ones showing low adherence.

Conclusions

Half of the treated patients had good adherence to treatment and a better TSH control, in comparison to the others. Most of them achieved a good control at the third trimester of pregnancy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04483-8.

Prevalence of Hypothyroidism in Pregnant Women in India: A Meta-Analysis of Observational Studies

INTRODUCTION

This meta-analysis was conducted to estimate the prevalence of hypothyroidism among pregnant women in India.

METHODS

We searched PubMed, Web of Science, Scopus, Google Scholar, and Shodhganga (Indian thesis repository) for observational studies, providing prevalence of hypothyroidism among pregnant women in India. Systematic study selection and data extraction procedures were followed. Quality assessment of each study was done using JBI critical appraisal checklist. The random effects model was used for pooling the effect sizes. Publication bias was assessed using the funnel plot and rank correlation test. I 2 statistics was used to measure heterogeneity across the studies. Heterogeneity in the pooled estimates was further explored with subgroup analyses and meta-regression analysis.

RESULTS

Sixty-one studies were found eligible and included in this review. The pooled estimate of the prevalence of hypothyroidism in pregnant women was 11.07% (95% CI: 8.79-13.84, I 2 = 99%). Pooled prevalence estimates of subclinical and overt hypothyroidism are 9.51% (95% CI: 7.48-12.04, I 2 = 98%) and 2.74% (95% CI: 2.08-3.58, I 2 = 94%).

CONCLUSION

We documented 11.07% pooled prevalence of hypothyroidism in pregnant women in India.