Subclinical Hypothyroidism In Pregnant Women Research Articles

The Effects of Maternal Smoking on Thyroid Function: Findings from Routine First-Trimester Sonographic Anomaly Screening.

This study aimed to assess the effect of tobacco exposure on maternal thyroid function and investigate its relationship to subclinical hypothyroidism in pregnant women during the first trimester. A comparison of maternal thyroid function was made on 45 smokers, who composed the study group, and 72 non-smokers, pregnant women, who constituted the control group. After determining smokers by questionnaire, carbon monoxide (CO) levels in the expiratory air of the participants in both groups were measured and recorded, and the smokers' exposure was objectively confirmed. Smoking and non-smoking pregnant women were similar regarding body mass index (BMI). While the TSH and fT4 levels were respectively 1.48 mlU/L and 11.43 pmol/L in pregnant women who smoked, that ratio changed to 1.72 mlU/L and 11.17 pmol/L in the non-smokers' group. But the differences between the groups were not statistically significant (p=0.239, p=0.179). Even though the rate of subclinical hypothyroidism was 8.9% in the smoking group, it was approximately 19.4% in the non-smoker group; the difference was not statistically significant (p=0.187). This study proved that there is no statistically significant difference between maternal serum TSH and fT4 levels and the rate of subclinical hypothyroidism in smokers during pregnancy in the first trimester.

Associations between exposure to phthalates and subclinical hypothyroidism in pregnant women during early pregnancy: A pilot case-control study in China

Phthalates are environmental endocrine disruptors with thyroid-disrupting properties; however, the association between phthalate exposure and subclinical hypothyroidism (SCH) during pregnancy is unknown. We recruited a study population from a cohort of pregnant women in Beijing, China, and conducted the present pilot case-control study of 42 SCH cases and 84 non-SCH controls matched with age and body mass index (BMI). Serum levels of thyroid peroxidase antibody, free thyroxine (FT4), thyroid-stimulating hormone (TSH), and urinary levels of ten phthalate metabolites during early pregnancy were measured. Urinary monoethyl phthalate (MEP) levels in SCH cases were observably higher than those in controls (p = 0.01). Conditional logistic regression analysis revealed that mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), MEP, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and di-(2-ethylhexyl) phthalate (ΣDEHP) were significantly associated with a higher risk of SCH during early pregnancy (adjusted odds ratios = 1.89, 1.42, 1.81, and 1.92, respectively). Concomitantly, multiple linear regression analysis showed that MECPP, MEOHP, and ΣDEHP were positively associated with TSH and FT4 × TSH in the entire study population. Bayesian kernel machine regression analysis and stratified analysis by BMI revealed upward tendencies in the serum levels of TSH and FT4 × TSH. In summary, exposure to phthalates, especially DEHP, may be associated with a higher risk of SCH during early pregnancy, and a possible mechanism is the disruption of the hypothalamus-pituitary-thyroid axis.

A prospective observational study on maternal thyroid-stimulating hormone and its impact on maternal and perinatal outcome

Background: Numerous hormonal changes and metabolic demands occur during pregnancy, resulting in complex changes in maternal thyroid function. Thyroid disorder is the second most common endocrine disorder found in pregnancy next to the diabetes group. It affects 1–2% of women of reproductive age. Overt hypothyroidism complicates 0.3–0.5% of pregnancies. The incidence of subclinical hypothyroidism in pregnant women is about 2–3%. Hyperthyroidism is present in 0.1–0.4%. Aims and Objectives: The aim of the study was to assess the maternal thyroid function test during pregnancy and its effect on maternal and fetal outcomes. Materials and Methods: A prospective observational study was conducted in the Department of Obstetrics and Gynaecology at Dhanalakshmi Srinivasan Medical College and Hospital, Tamil Nadu over a period of 1 year February 2019 to January 2020. The study is to screen pregnant women for thyroid disorders based on their serum thyroid stimulating hormone (TSH) at the first antenatal visit and its impact on maternal and perinatal outcomes. Results: In our study, overall thyroid abnormality incidence was found to be 5.5%. It is statistically significant (P<0.001). Subclinical hypothyroid was found as a major thyroid disorder in the study population (significant P<0.002). In the study overt hyperthyroidism: 0.5%, subclinical hypothyroidism: 3.5%, primary hypothyroidism 1.5% was found. More than 54% of the study population had no high-risk factors and were found to have a thyroid disorder. In our study, maternal complications in women with thyroid disorders were analyzed. One woman with overt hypothyroidism, one with subclinical hypothyroidism developed mild preeclampsia. One hypothyroid woman had preterm labor at 32 weeks of gestational age. Maternal complications were less inadequately treated patients resulting in a normal incidence of these complications. In our study birth weight of the babies, <2.5 kg was 18.2%, 2.5–3 kg was 63.6%, and >3 kg was 18.2%. Perinatal outcomes were in terms of preterm, intrauterine growth restriction, low birthweight, and fetal distress. Conclusion: All pregnant women irrespective of their low risks or high risks for a thyroid disorder should be screened for serum TSH at the first booking visit to prevent the maternal and perinatal complications of thyroid disorders and close monitoring and effective treatment could be provided to them.

Frequency of anti TPO positive subclinical hypothyroidism in pregnancy.

Objective: To determine the frequency of anti TPO positive subclinical hypothyroidism in pregnancy. Study Design: Cross Sectional Study. Setting: Outpatient Departments of Gynaecology & Obstetrics and Medicine at a Tertiary Care Hospital of Quetta, Pakistan. Period: May 2020 to May 2021. Material & Methods: All the pregnant women of age 18-45 years whose TSH was above 2.5 uIU/ml and less than 10 uIU/ml and Total T4 was between 5.5-16 ug/dl was said to be having subclinical hypothyroidism and is included in the study. Their age, TSH value, anti TPO and history of prior miscarriage was documented in proforma. Those pregnant women who were already on levothyroxine and taking biotin while performing TSH test were excluded from the study. For analysis SPSS version 20 was used. The calculated sample size was 42 with confidence interval of 95%. Results: Out of forty two pregnant women with subclinical hypothyroidism, 19 pregnant women were anti TPO positive (45.2%). The mean TSH was 5.26 uIU/ml. The highest number of subclinical hypothyroidism (50%) was in age group of 36-45 years. There was prior history of miscarriage in 9 pregnant women (21.4%). Conclusion: The frequency of anti TPO antibodies is high in subclinical hypothyroidism in pregnant women which increases with age and has association with history of prior miscarriage.

Pregnancy outcomes and thyroid dysfunction: preterm birth risk assessment

Introduction. Subclinical hypothyroidism occurs in 2–3% of pregnant women and is often associated with pregnancy complications, including preterm birth.Aim – to study correlations between thyroid dysfunction and pregnancy outcomes.Materials and methods. 64 clinical cases of managing pregnant women in the Perinatal Center (Tyumen) were analyzed for 2017– 2021: 28 women with thyroid-stimulating hormone (TSH) > 2.5 mU/l, 36 women with TSH ≤ 2.5 mU/l) during the entire period of pregnancy. Quantitative features are described by absolute and relative (percentage) indicators. The probability of outcome depending on the presence of a clinical-amnestic factor was assessed by determining the relative risk (RR) and 95% confidence interval (CI). The level of statistical significance in testing the null hypothesis is p < 0.05.Results. There were no differences in pregnant women with and without subclinical hypothyroidism when considering such medical and social factors as age, marital status, work, education, nicotine addiction, obesity, kidney disease. An increased risk of preterm delivery was found in patients with a TSH level > 2.5 mU/l: RR 1.41 (0.59–3.37), especially against the background of a positive test for antibodies to thyroperoxidase: RR 1.63 (0.62–4.28). In the absence of treatment, the risk of early delivery, preterm birth, preeclampsia was revealed.Conclusions. A universal approach to determining the threshold values of TSH for the diagnosis of subclinical hypothyroidism in pregnant women, to the need and tactics of its treatment has not been developed. Diseases of the thyroid gland are endemic for Western Siberia, often associated with iron deficiency anemia, their high frequency in the anamnesis of pregnant women is noted. Establishing a correlation between subclinical hypothyroidism, hormonal correction and pregnancy complications requires further research. An obstacle is the lack of proper diagnosis of the TSH level in women who give birth on an emergency basis in early gestational periods.

Субклинический гипотиреоз у беременных в йододефицитном регионе: лечить или нет?

Заболевания щитовидной железы в структуре эндокринной патологии в последние годы занимают первые места. По данным Министерства здравоохранения Украины, за последние 5 лет количество заболеваний щитовидной железы увеличилось в 5 раз, причем данный показатель существенно отличается в различных регионах страны в зависимости от совокупности факторов внешней среды (удаленный стохастический эффект аварии на Чернобыльской АЭС, йодный дефицит, образ жизни, стресс, нерациональное питание, недостаточность микроэлементов, сопутствующие заболевания и т.д.). При этом известна тесная функциональная взаимосвязь тиреоидной и репродуктивной систем, что приводит к высокой вероятности развития объединенных нарушений при расстройствах одной из этих звеньев гомеостаза. Проблема нарушений репродуктивного здоровья вызывает особенно серьезное беспокойство во всем мире и является актуальной по изучению характера влияния заболеваний щитовидной железы на беременность. Показатели заболеваемости патологиями щитовидной железы и их распространенности отличаются в разных регионах страны в зависимости от влияния факторов внешней среды и их комбинации, одним из таких является дефицит йода. Увеличение количества мертворожденных младенцев, преждевременное прерывание беременности, бесплодие, тугоухость и косоглазие новорожденных, задержка физического, полового и интеллектуального развития детей, рост показателей сердечно-сосудистых заболеваний — далеко не полный перечень негативного влияния йодного дефицита на человека. Наиболее частыми последствиями йодного дефицита у беременных является субклинический гипотиреоз. Субклинический гипотиреоз ассоциируется со многими неблагоприятными событиями во время беременности и неонатальными последствиями. Изучение особенностей течения субклинического гипотиреоза у беременных в йододефицитном регионе на сегодня остается актуальной проблемой. В статье представлен анализ публикаций баз данных PubMed, Medline за последние десятилетия.

Screening determination of thyroid stimulating hormone in diagnosis of subclinical hypothyroidism in pregnant women: versions and contraversions

The work is devoted to the necessity of conducting a screening study of thyroid function in women in the pre-gravidar period and during gestation. Pathological conditions of the thyroid gland are one of the most common diseases of the endocrine system, second only to diabetes mellitus in prevalence. At the same time, in recent years, there has been an increase in thyroid insufficiency. Clinical and subclinical hypothyroidism are the most common hormonal dysfunctions during pregnancy, which have a negative impact on the course of gestation and fetal development. At the same time, subclinical hypothyroidism is an easily treatable disease that reduces the pregnancy related morbidity of the mother and fetus. Screening only at-risk patients probably skips most cases. Therefore, guidelines should be established for universal screening of thyroid dysfunction in the pre-gravidar period and during pregnancy with their own ranges for thyroid stimulating hormone during gestation, calculated taking into account regional, ethnic and population characteristics. Levothyroxine replacement therapy in a woman with subclinical hypothyroidism in the pre-gravidar period and during pregnancy should begin immediately after the diagnosis of this condition and be adequate in terms of timing and dose.

Hearing outcome in infants following correction of maternal hypothyroidism during pregnancy

PurposeThere is significant prevalence of overt and subclinical hypothyroidism in pregnant women in rural areas. Maternal hypothyroidism is known to cause congenital hypothyroidism resulting in sensorineural hearing loss. Anti-Thyroperoxidase antibodies are known to cross placental barrier. There is no literature on hearing assessment in infants born to women whose hypothyroidism was corrected during pregnancy. Do these infants suffer hearing loss? Our study addresses this question. Methods140 infants born to women on treatment for hypothyroidism during pregnancy and 140 infants born to euthyroid women were evaluated for hearing by Brainstem Evoked Response Audiometrry at 1 and 4 months age. Anti-TPO antibodies were estimated at 4 months of age. ResultsThere was no clinical hearing deficit or delay in neurological development in infants born to women undergoing treatment for hypothyroidism during pregnancy. However wave V latency on BERA was slightly prolonged in them compared to infants born to euthyroid women. There was absence of wave V when maternal subclinical hypothyroidism persisted till parturition. However within 6–8months of age the wave V latencies corrected to normal. Anti-TPO antibodies were within normal range at 4months age. ConclusionMaternal hypothyroidism when corrected before parturition does not affect hearing in the infants clinically. The mild delay in wave V on BERA corrects within first year of life. However larger studies to assess hearing in infants born to women having overt hypothyroidism during first trimester of pregnancy may be desirable to assess whether hearing is adversely affected in them.

Subclinical hypothyroidism in pregnancy: controversies on diagnosis and treatment.

The negative impact of even subtle maternal thyroid hormone deficiency on the pregnancy outcome and intellectual development of the progeny has been known for many years, but unfortunately the diagnosis and treatment of subclinical hypothyroidism in pregnant women still evokes controversies. Due to physiological changes in thyroid function and thyroid hormones metabolism during pregnancy, the trimester‑specific reference ranges for thyroid‑stimulating hormone (TSH) and free thyroid hormones should be established. However, because of interassay variability and other confounders including ethnicity and iodine intake, such norms are reliable only for local populations and a specific laboratory method. In turn, the fixed reference ranges suggested by endocrine societies may carry a risk of misclassificating some healthy pregnant women to be hypothyroid. The effect of levothyroxine treatment on pregnancy and children's cognitive outcomes remains unclear. Therapeutic benefits in decreasing miscarriage and preterm delivery rates were observed when intervention was held in the first trimester in women with a TSH level between 2.5 to 10 mU/l, mainly higher than or equal to 4 mU/l. The possible harmful effect of treatment includes preterm delivery, gestational diabetes, hypertension, and pre‑eclampsia. The only 3 prospective, randomized, placebo‑controlled trials evaluating the efficacy of levothyroxine therapy on children's intelligence quotient were started in the second trimester, which may be too late to demonstrate differences between treatment and placebo groups. Awaiting the results of future trials, clinicians should be aware of the fact that low‑dose levothyroxine at a daily dose of 25 to 50 µg is probably not harmful and may be beneficial, but the routine implementation of the therapy in each pregnant women with a TSH level exceeding 2.5 mU/l seems too premature.

Новости клинических рекомендаций по диагностике и лечению субклинического гипотиреоза у беременных женщин

Новости клинических рекомендаций по диагностике и лечению субклинического гипотиреоза у беременных женщин

Prevalence of thyroid function in pregnant and lactating women in areas with different iodine levels of Shanxi province

Objective: To investigate the effects of high iodine intake on thyroid function in pregnant and lactating women. Methods: A cross sectional epidemiological study was conducted among 130 pregnant women and 220 lactating women aged 19-40 years in areas with high environment iodine level (>300 μg/L) or proper environment iodine level (50-100 μg/L) in Shanxi in 2014. The general information, urine samples and blood samples of the women surveyed and water samples were collected. The water and urine iodine levels were detected with arsenic and cerium catalysis spectrophotometric method, the blood TSH level was detected with electrochemiluminescence immunoassay, and thyroid stimulating hormone (FT(4)), antithyroid peroxidase autoantibody (TPOAb) and anti-thyroglobulin antibodies (TGAb) were detected with chemiluminescence immunoassay. Results: The median urine iodine levels of the four groups were 221.9, 282.5, 814.1 and 818.6 μg/L, respectively. The median serum FT(4) of lactating women in high iodine area and proper iodine area were 12.96 and 13.22 pmol/L, and the median serum TSH was 2.45 and 2.17 mIU/L, respectively. The median serum FT(4) of pregnant women in high iodine area and proper iodine area were 14.66 and 16.16 pmol/L, and the median serum TSH was 2.13 and 1.82 mIU/L, respectively. The serum FT(4) levels were lower and the abnormal rates of serum TSH were higher in lactating women than in pregnant women in both high iodine area and proper iodine area, the difference was statistically significant (FT(4): Z=-6.677, -4.041, P<0.01; TSH: Z=8.797, 8.910, P<0.01). In high iodine area, the abnormal rate of serum FT(4) in lactating women was higher than that in pregnant women, the difference was statistically significant (Z=7.338, P=0.007). The serum FT(4) level of lactating women in high iodine area was lower than that in proper iodine area, the difference was statistically significant (Z=-4.687, P=0.000). In high iodine area, the median serum FT(4) in early pregnancy, mid-pregnancy and late pregnancy was 16.26, 14.22 and 14.80 pmol/L, respectively, and the median serum TSH was 1.74, 1.91 and 2.38 mIU/L, respectively. In high iodine area, the serum FT(4) level in early pregnancy was higher than that in mid-pregnancy and late pregnancy, and the serum TSH level was lower than that in mid-pregnancy and late pregnancy, the difference was statistically significant (FT(4): Z=-2.174, -2.238, P<0.05; TSH: Z=-2.985, -1.978, P<0.05). There were no significant differences in the positive rates of serum thyroid autoantibodies among the four groups of women and women in different periods of pregnancy (P>0.05). The morbidity rates of subclinical hyperthyroidism in pregnant women and lactating women in high iodine area were obviously higher than those in proper iodine areas, the difference was statistically significant (χ(2)=5.363, 5.007, P<0.05). Conclusions: Excessive iodine intake might increase the risk of subclinical hypothyroidism in pregnant women and lactating women. It is suggested to strengthen the iodine nutrition and thyroid function monitoring in women, pregnant women and lactating women in areas with high environmental iodine.

Prevalence of subclinical hypothyroidism in pregnancy in Saudi Arabia

objectives:To estimate the prevalence of subclinical hypothyroidism (SCH) in Saudi Arabia and assess the need for an SCH screening program.Methods:This cross-sectional study was conducted at King Abdulaziz Medical City and the Khashmulaan Clinic at the National Guard Health Affairs, Riyadh, Saudi Arabia in August 2016. All women attending the antenatal clinics were invited to participate in the study. In addition, data were retrieved from the files of pregnant women who had been screened for hypothyroidism from January 2016 to August 2016. A total of 384 pregnant women were included in the study.Results:The prevalence of SCH in pregnant women in this study was 50/384 (13%) with 95% confidence intervals (CIs): 9.82%-16.80%. Pregnant women who were randomly screened using a survey (n=127) were 3 times more likely (OR: 3.1; 95% CI: 1.182 to 8.704, p=0.022) to have SCH compared to pregnant women who were screened based on their physician’s judgement (n=257). Results showed older age (≥40 years) was associated with an insignificant decrease in the risk of SCH.Conclusion:Random screening for SCH in pregnant women showed a higher prevalence in comparison to women who were screened as a result of physician referrals. The results highlight the urgent need for larger studies to investigate the prevalence of SCH as well as the need for an SCH screening program.

Maternal thyroid parameters in pregnant women with different ethnic backgrounds: Do ethnicity‐specific reference ranges improve the diagnosis of subclinical hypothyroidism?

Guidelines on the management of thyroid dysfunction during pregnancy have recently been updated and, for the diagnosis of subclinical hypothyroidism (SCH), a thyroid-stimulating hormone (TSH) upper reference limit (cut-off) of 4.0mIU/L has been proposed when no institutional values are available. It is also suggested that serum TSH and thyroid autoimmunity (TAI) may be different according to the ethnic background of the women. We therefore determined the prevalence of TAI and SCH in pregnant women with different ethnic backgrounds and, to define SCH, we used different first trimester TSH upper reference cut-offs (institutional, ethnicity-specific, 2.5mIU/L [Endocrine Society] and 4.0mIU/L [American Thyroid Association]). Cross-sectional data analysis of 1683 pregnant women nested within an ongoing prospective database of pregnant women. The study was performed in a single centre in Brussels, Belgium. During the first antenatal visit, thyroid peroxidase antibodies (TPO-abs), TSH and free T4 (FT4) were measured and baseline characteristics recorded. Data from 481 women with sub-Saharan (SaBg; 28.6%), 754 North African (NaBg; 44.8%) and 448 Caucasian (CaBg; 26.6%) backgrounds were analysed. For the calculation of TSH reference ranges, women with TAI, outliers, twin and assisted pregnancies were excluded. The prevalence of TAI was significantly lower in the SaBg group than in NaBg and CaBg groups (3.3% vs 8.6% and 11.1%; P<.001, respectively). Median TSH was significantly lower in SaBg and NaBg groups as compared with the CaBg group (1.3 and 1.4 vs 1.5 mIU/L; P=.006 and .014, respectively). The prevalence of women with SCH was comparable between all groups when 2.5 mIU/L was used as cut-off, but when 4.0mIU/L or the institutional cut-off (3.74mIU/L) was used, it was significantly higher in the CaBg group vs the NaBg group (5.4% vs 2.1% and 7.1% vs 3.3%, P=.008 and .013, respectively). The use of ethnicity-specific cut-offs did not change the prevalence of SCH as compared to the use of institutional cut-offs. However, when these cut-offs were used, the prevalence of SCH reduced by >70% (4.5% instead of 16.7%; P<.001) relative to the 2.5mIU/L cut-off. Pregnant women with a sub-Saharan African background had a lower prevalence of TAI and TSH levels as compared with women from other backgrounds. The use of ethnicity-specific TSH cut-offs in early pregnancy was not more specific for the diagnosis of SCH as compared to the use of the institutional cut-off.

Subclinical hypothyroidism in pregnancy: An emerging problem in Southern West Bengal: A cross-sectional study.

Background:Prevalence of subclinical hypothyroidism (SCH) in pregnancy varies widely in different parts of our country, but it has multiple adverse outcomes in both the mother and fetus.Objectives:This study was conducted to evaluate the prevalence of SCH in pregnant women during the first trimester and to identify the prevalence of thyroid autoimmunity in pregnant women.Materials and Methods:This cross-sectional study (March 2014 to February 2015) was conducted among the pregnant women attending antenatal clinic in their first trimester at a tertiary care center. Morning samples of study participants were analyzed for free thyroxin (FT4), thyroid stimulating hormone (TSH), and thyroid peroxidase antibody (TPO Ab). Data expressed as mean ± standard deviation and percentage (%) as applicable.Results:Of the 510 subjects, 168 had TSH value >2.5 μIU/ml (32.94%) with normal FT4 and they were diagnosed as SCH. TSH level >4.5 μIU/ml was estimated in 13.92% (71) of the subjects. TPO Ab was positive in 57 (33.93%) of subclinical hypothyroid and 5 (1.47%) of normal subjects. 70.42% (50) of the subjects with TSH >4.5 μIU/ml had positive TPO Ab.Conclusions:Prevalence of SCH is high in South Bengal and routine thyroid screening at the first antenatal visit should be done to reduce the social and financial burden caused by SCH.

Genetic association study of phosphodiesterase 8B gene with subclinical hypothyroidism in pregnant women

Objective: To explore whether phosphodiesterase 8B (PDE8B) gene is involved in the etiology of subclinical hypothyroidism (SCH) in pregnant women. Methods: A total of 180 pregnant patients with SCH and 311 healthy, pregnant control subjects were recruited in this study to detect 4 (rs4704397, rs6885099, rs2046045, and rs12514694 in PDE8B) single nucleotide polymorphisms (SNPs). Univariate associations were studied using Pearson’s χ2 test for categorical variables and Student t/ANOVA tests for continuous ones. Nonparametric Kruskal–Wallis test were used to study the associations of TSH level in different genotypes. Genotyping of SNPs was performed by the MassARRAY® iPLEX® Gold SNP genotyping analysis technique. The SHEsis program was used to analyze the genotyping data. Results: There was a significant difference in the rate of high TSH in three genotypes of rs4704397 in all pregnant women. After adjusting for multiple testing by the program SNPSpD, allelic frequencies of rs4704397 (p = 0.016, OR = 1.692), rs6885099 (p = 0.031, OR = 0.621), and rs2046045 (p = 0.023, OR = 0.602) in PDE8B gene showed significant differences between patients with SCH and control subjects. There were no significant differences of genotype frequencies between patients and controls at any of the analyzed SNPs (p > 0.05).The haplotypes ‘‘A G C G’’ (p = 0.002; OR, 1.533; 95% CI, 1.172–2.006) and “G A A G” (p = 0.014; OR, 0.576; 95% CI, 0.369–0.899) in PDE8B were observed to be significantly associated with SCH in pregnant women. Conclusion: Genetic variation of the PDE8B gene may be involved in the etiology of SCH in pregnant women.

The development of guidelines for management of thyroid diseases in pregnancy – current status

The development of guidelines for management of thyroid diseases in pregnancy – current status

Thyroid Dysfunction during Late Gestation Is Associated with Excessive Iodine Intake in Pregnant Women

Adequate iodine intake during pregnancy is essential for both the synthesis of maternal thyroid hormones and the maintenance of normal fetal brain development. Scant evidence is available on the effects of excessive iodine intake during pregnancy. The study assesses the relationship between iodine nutritional status and thyroid function of pregnant women with excessive iodine intake during late gestation. A cross-sectional study of 384 pregnant women was carried out in Tianjin and Haixing from April to October in 2010. Morning urine samples and blood samples were obtained from all subjects. Serum levels of free T(3), free T(4), and sensitive TSH and urinary iodine concentration were measured. The median urinary iodine concentration of pregnant women with excessive iodine intake was significantly higher than those with adequate iodine intake (P < 0.001). The prevalence of thyroid disease, especially subclinical hypothyroidism, in pregnant women with excessive iodine intake was significantly higher than in those with adequate iodine intake (P < 0.05). Subclinical hypothyroidism was the most frequent pattern of thyroid disease for pregnant women and those with positive or negative thyroid autoantibodies. Living with high water iodine content and having urinary iodine concentration higher than 250 μg/liter are associated risk factors for subclinical hypothyroidism in pregnant women (OR(1) = 41.822, OR(2) = 6.202; P < 0.05, where OR(1) is the odds ratio for living with high water iodine content and hypothyroidism and OR(2) is the odds ratio for urinary iodine concentration >250 μg/liter and hypothyroidism). Excessive iodine intake during late pregnancy may lead to maternal thyroid dysfunction, particularly subclinical hypothyroidism. The appropriate measurements should be performed to monitor the onset of hypothyroidism in pregnant women with excessive iodine intake.

Controlled or uncontrolled clinical and subclinical hypothyroidism in pregnant women and its effect on obstetrical and neonatal outcome

Objetive To investigate the obstetrical and neonatal outcomes of pregnant women with hypothyroidism or subclinical hypothyroidism.Methods One hundred and sixty-eight pregnant women with clinical or subclinical hypothyroidism during pregnancy,including 9 controlled hypothyroidism,29 uncontrolled hypothyroidism and 130 subclinical hypothyroidism,were enrolled in this study.The general clinical information,obstetrical complications and neonatal outcomes of these pregnant women were compared with that of 180 healthy pregnant women who delivered during the same period.Results Compared with control group,there were no significant differences in the levels of serum free triiodothyronine( FT3 ),free thyroxine ( FT4 ),thyrotropin-stimulating hormone (TSH) in the controlled hypothyroidism group in the third trimester [(3.68 ±1.11 ) pmol/L vs (3.19 ±0.33) pmol/L,(15.48 ±4.14) pmoL/L vs (13.95 ± 1.68) pmol/L,1.87 mU/L vs 1.76 mU/L,P ＞0.05].However,in the second and third trimester,the levels of FT3,FT4 in the uncontrolled hypothyroidism group were lower,while the levels of TSH were higher than in control group [(2.71 ±0.80) pmol/L vs (3.14 ± 0.34) pmoL/L,(10.94 ± 2.68) pmol/L vs (14.25 ±2.01) pmol/L,5.62 mU/L vs 2.28 mU/L,( 2.34 ± 0.70 ) pmol/L vs ( 3.19 ± 0.33 ) pmol/L,( 10.16 ± 1.65 ) pmol/L vs (13.95 ± 1.68) pmoL/L,7.13 mU/L vs 1.76 mU/L,t =2.754～9.15,P ＜0.01],the levels of TSH in the subclinical hypothyroidism were higher than in control group ( t =18.28,18.57,P ＜0.01 ).There was no adverse perinatal outcome of neonate happened in controlled hypothyroidism group.In contrast,the incidences of adverse perinatal outcomes and complications in the uncontrolled hypothyroidism group were higher than that in the control group ( 17.2％ vs 2.8％,37.9％ vs 5.6％,x2 =11.47,28.97,P ＜0.01 ).Compared with that of control group,the incidences of adverse obstetrical outcomes in pregnant women with subclinical hypothyroidism were increased (40.0％ vs 5.6％,x2 =52.97,P ＜ 0.01 ).Conclusions The rate of adverse obstetrical outcomes and complications is increased in women with clinical or subclinical hypothyroidism.But the incidence of adverse outcomes would decrease if hypothyroidism is controlled by treatment. Key words: Pregnancy complications/TH ; Hypothyroidism/CO/TH; Pregnancy outcome

Obstetric outcome in women with hepatitis C virus infection and thyroid dysfunction

OBJECTIVES. To determine the incidence of thyroid abnormality in pregnant women with hepatitis C virus (HCV) infection and evaluate pregnancy outcomes with respect to thyroid function status. DESIGN. Prospective cohort study. SETTING. Tertiary care hospital. POPULATION. Pregnant women with HCV infection. METHODS. Seventy-eight HCV positive women had radioimmunoassay thyroid function tests. All were followed until delivery. Pregnancy outcomes were compared in women with and without subclinical hypothyroidism. MAIN OUTCOME MEASURES. Maternal and perinatal outcomes. RESULTS. Of 78 anti-HCV antibody positive pregnant women, 13 (16.7%) had abnormal thyroid-stimulating hormone (TSH) (>5 mIU/L; hypothyroid group) and the remaining 65 (83.3%) had normal TSH values (euthyroid group). None had abnormal free T4 levels. None showed evidence of fetal distress in labor or fetal asphyxia. In the hypothyroid group, 23% compared to 6.2% in euthyroid group underwent cesarean section (p=0.07). The incidence of preterm delivery (7.7% vs. 24.6%; p=0.28), mean gestation at delivery (38.2+/-1.8 vs. 37.5+/-1.8 weeks, p=0.19), and birthweight (2,687+/-430 g vs. 2,846+/-379 g, p=0.18) was comparable. Neonatal nursery admissions were comparable. CONCLUSION. The presence of subclinical hypothyroidism in pregnant women with HCV infection does not adversely affect short-term pregnancy outcomes.

Subclinical hypothyroidism

Mild or subclinical hypothyroidism is characterized by normal serum free thyroxine concentrations with elevated serum thyroid-stimulating hormone concentrations. Subclinical hypothyroidism is relatively prevalent in the general population, especially among women and the elderly. The main cause of subclinical hypothyroidism is autoimmune chronic thyroiditis. The present report reviews the most important and recent studies on subclinical hypothyroidism, and discusses the most controversial aspects of this topic. Several studies have demonstrated that subclinical hypothyroidism may affect both diastolic and systolic cardiac function. It may also worsen many risk factors for cardiovascular disease, including hypertension, abnormal endothelial function, and elevated low-density lipoprotein cholesterol concentrations. Furthermore, a growing body of evidence suggests that subclinical hypothyroidism may cause symptoms or progress to symptomatic overt hypothyroidism. Prompt treatment of subclinical hypothyroidism in pregnant women is mandatory to decrease risks for pregnancy complications and impaired cognitive development in offspring. Children with subclinical hypothyroidism should be treated to prevent growth retardation. Whether nonpregnant adult patients with subclinical hypothyroidism should be treated, and at what thyroid-stimulating hormone values, is debatable.