Thyroid Hormones In Pregnant Women Research Articles

Relationship Between Gestational Diabetes and Thyroid Hormones in Pregnant Women

Relationship Between Gestational Diabetes and Thyroid Hormones in Pregnant Women

Ambient pm2.5 and thyroid hormones in pregnant women in Puerto Rico

Ambient pm2.5 and thyroid hormones in pregnant women in Puerto Rico

Reference Intervals of Thyroid Hormones During Pregnancy Established by Three Statistical Methods.

Monitoring the thyroid hormones during pregnancy is of great importance for fetal growth and development. Throughout the whole pregnancy, there is constant fluctuation in the thyroid hormone reference intervals (RIs). The purpose of this study is to determine method- and trimester-specific RIs for thyroid-stimulating hormone, free thyroxine, and free triiodothyronine in pregnant women in China. In this study, 2,167 women with normal pregnancies (first trimester, n = 299; second trimester, n = 1,032; third trimester, n = 836) and 4,231 healthy nonpregnant women subjects were recruited. Serum thyroid-stimulating hormone (TSH), free thyroxine (fT4), and free triiodothyronine (fT3) concentrations were measured using electrochemiluminescence immunoassays in Abbott Alinity i analyzer. Following the exclusion of outliers, the RIs were determined using three statistical techniques: the non-parametric method, the Hoffmann method, and the Q-Q plot method. Pregnant women's levels of these three thyroid hormones differ markedly from those of healthy non-pregnant women. In addition, the concentrations of these three hormones change considerably over the course of the three phases of pregnancy. The Q-Q plot method offered more comparable RIs with the non-parametric method in healthy non-pregnant women than the Hoffmann method. Three statistical techniques were used to construct the trimester-specific RIs of thyroid hormones in pregnant women, and there was little difference between them all. The RIs by the non-parametric and Q-Q plot methods indicated closer RIs, and the RIs by the Hoffmann approach were higher and wider than those by the other two methods. For thyroid hormones, trimester-specific RIs are required. The RIs determined by non-parametric and Q⁃Q plot indirect calculation could be used as the alternative method.

Associations of bisphenol exposure with thyroid hormones in pregnant women: a prospective birth cohort study in China.

Bisphenols are endocrine disruptor chemicals that disrupt thyroid hormone homeostasis. However, evidence on the effects of bisphenol mixtures on thyroid hormones are insufficient. Therefore, the present study aimed to explore the effects of bisphenol substitutes and bisphenol mixtures on thyroid hormones during pregnancy. The study was conducted among 446 pregnant women in the Guangxi Zhuang Birth Cohort (GZBC), China. In multiple linear regressions, compared with the low-exposure group, bisphenol S (BPS) concentrations in the middle-exposure group led to a 10.90% (95% CI: - 18.16%, - 2.99%) decrease in triiodothyronine (T3) levels in the first trimester; tetrabromobisphenol A (TBBPA) levels in the middle-exposure group led to an 8.26% (95% CI: - 15.82%, - 0.01%) decrease in T3 levels in the first trimester; bisphenol B (BPB) levels in the middle-exposure group led to higher free thyroxine (FT4) levels (9.84%; 95% CI: 1.73%, 18.60%) in the second trimester; bisphenol F (BPF) in the middle-exposure group led to higher FT4 levels (8.59%, 95% CI: 0.53%, 17.31%) in the second trimester; and TBBPA levels in the high-exposure group led to a 9.39% (95% CI: 1.46%, 17.93%) increase in FT4 levels in the second trimester. The Bayesian kernel machine regression (BKMR) and restricted cubic spline (RCS) models showed a U-shaped dose-response relationship between bisphenol A (BPA) and free triiodothyronine (FT3) (p < 0.01) as well as BPS and FT4 (p < 0.05). Nonlinear relationships were also observed between the bisphenol mixture and FT3. Overall, maternal bisphenol exposure affected thyroid hormone levels during pregnancy. This study provides evidence that BPB, BPF, BPS, and TBBPA are unsafe substitutes for BPA, as well as the overall effect of bisphenols on adverse health in human beings.

Associations between Oxidative/Nitrosative Stress and Thyroid Hormones in Pregnant Women-Tainan Birth Cohort Study (TBCS).

Oxidative and nitrosative stress have been linked to thyroid function in both animal and human studies. In the present study, the associations between oxidative and nitrosative stress and thyroid hormones were investigated. Measurements were obtained from 97 Taiwanese pregnant women at the first, second, and third trimesters. Levels of five oxidative and nitrosative stress biomarkers (8-hydroxy-2′-deoxyguanosine [8-OHdG], 8-nitroguanine [8-NO2Gua], 4-hydroxy-2-nonenal-mercapturic acid [HNE-MA], 8-isoprostaglandin F2α [8-isoPGF2α], and malondialdehyde [MDA]) were measured using urine samples, and levels of five thyroid hormones (triiodothyronine [T3], thyroxine [T4], free T4, thyroid-stimulating hormone [TSH], and T4-binding globulin [TBG]) were measured in blood samples. Multiple linear regressions and linear mixed-model regressions were conducted to determine the associations between oxidative or nitrosative stress biomarkers and thyroid hormones in pregnant women. We found that TSH was negatively and significantly associated with 8-NO2Gua (−14%, 95% CI [−26.9% to −1.1%]) and HNE-MA (−23%, 95% CI [−35.9% to −10.0%]) levels. However, T4 (3%, 95% CI [0.2%–5.8%]) and free T4 (4.3%, 95% CI [0.8%–7.8%]) levels were positively and significantly associated with 8-NO2Gua. The T4 to TBG and free T4 to TBG ratios were positively and significantly associated with 8-NO2Gua level (T4/TBG: 3.6%, 95% CI [0.5%–6.7%]; free T4/TBG: 5.6%, 95% CI [0.2%–11.1%]). However, the TSH to T4 ratio was negatively and significantly associated with 8-NO2Gua level (−17.3%, 95% CI [−30.4% to −4.3%]). The T3 to TSH ratio was positively and significantly associated with HNE-MA level (25.2%, 95% CI [11.2%–39.2%]). However, the TSH to T4 and TSH to free T4 ratios were negatively and significantly associated with HNE-MA level (TSH/T4: −21.2%, 95% CI [−34.5% to −7.8%] and TSH/free T4: −24.0%, 95% CI [−38.3% to −9.6%]). Our findings suggest that an imbalance of oxidative and nitrosative stress may alter thyroid hormone homeostasis during pregnancy. Disruption of the maternal thyroid homeostasis during pregnancy would affect embryonic and fetal development.

Associations Between Prenatal Exposure to Air Pollution and Congenital Hypothyroidism.

Adequate thyroid hormone availability is required for normal brain development. Studies have found associations between prenatal exposure to air pollutants and thyroid hormones in pregnant women and newborns. We aimed to examine associations of trimester-specific residential exposure to common air pollutants with congenital hypothyroidism (CHT). All term infants born in Israel during 2009-2015 were eligible for inclusion. We used data on CHT from the national neonatal screening lab of Israel, and exposure data from spatiotemporal air pollution models. We used multivariable logistic regression models to estimate associations of exposures with CHT, adjusting for ethnicity, socioeconomic status, geographical area, conception season, conception year, gestational age, birth weight, and child sex. To assess residual confounding, we used postnatal exposures to the same pollutants as negative controls. The study population included 696,461 neonates. We found a positive association between third-trimester nitrogen oxide exposure and CHT (per interquartile-range change, odds ratio = 1.23, 95% confidence interval: 1.08, 1.41) and a similar association for nitrogen dioxide. There was no evidence of residual confounding or bias by correlation among exposure periods for these associations.

Prenatal Phthalates Exposure and Cord Thyroid Hormones: A Birth Cohort Study in Southern Taiwan.

Background: The regulation of thyroid hormones in the early stages of gestation plays a crucial role in the outcome of a pregnancy. Furthermore, thyroid hormones are fundamental for the fetal development of all organs, including endocrine hormone changes in uterus. Endocrine disrupting chemicals have been shown to have an effect on thyroid hormone homeostasis in newborns, which affects their later development. Few studies have proposed how phthalates could alter thyroid function through several mechanisms and the possible effects on thyroid hormone homeostasis of phthalates on pregnant women. However, the effects of cord blood phthalates and prenatal phthalate exposure on thyroid hormones in newborns remain unclear. Objectives: We aim to follow up on our previous established subjects and determine the correlation between phthalate exposure and thyroid hormones in pregnant women and newborns. Materials and methods: We recruited 61 pregnant women from the Obstetrics and Gynecology Department of a medical hospital in southern Taiwan and followed up. High performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) was used to analyze urine samples for five phthalate metabolites. Serum levels of thyroid hormones were analyzed using electrochemoluminescence immunoassay (ECLIA) method. We used Spearman and Pearson correlation coefficients to evaluate the correlation between each phthalate metabolites in serum and the thyroid hormone levels in fetus and parturient. Finally, multiple logistic regression was used to explore the relationship between hormones and their corresponding phthalate metabolites in cord blood. Results: High MBP in cord blood was correlated with negative cord serum TSH in newborns (r = −0.25, p < 0.06). By using multiple linear regression after adjusting for potential confounders (gestational and maternal age), cord serum MBP levels showed a negative association with cord serum TSH (β = 0.217, p < 0.05), cord serum T4 (β = 1.71, p < 0.05) and cord serum T4 × TSH (β = 42.8, p < 0.05), respectively. Conclusion: We found that levels of cord serum TSH and T4 in newborns was significantly negatively associated with cord serum MBP levels after adjusting for significant covariate. The fall in TSH in newborns may potentially be delaying their development.

Features of the content of homocysteine and thyroid hormones in pregnant women with uterine myoma

The purpose and objectives of the study is to assess the effect of hyperhomocysteinemia on the first trimester of gestation in women with uterine myoma. Relevance. Biochemical and hormonal changes that occur in the myometrium and the body of a woman as a whole, without preventing the onset of pregnancy, can have a significant effect on the formation of the chorion and the clinical course of the gestational process, provoking complications such as miscarriage. Material and research methods. To achieve this goal, we examined 182 pregnant women, of which the main group was 98 pregnant women with a verified diagnosis of uterine fibroids, which took place before gestation, but did not prevent pregnancy. The comparison group included 84 pregnant women without anamnestic indications of gynecological pathology and signs of fetoplacental insufficiency. Results. We made an attempt to highlight the features of the content of homocysteine and thyroid hormones in pregnant women with uterine myoma and the influence of these indicators on the onset of gestation. Considering the results obtained, we indicate that pregnant women with uterine fibroids and without a tumor had significant differences in individual values. Conclusions. In women with benign tumors of the uterus that are pregnant, the most common conditions in the first trimester are mild anemia and genital tract bleeding. Half of the observed pregnant women with uterine myoma have hyperhomocysteinemia and, in some of them, subclinical hypothyroidism. This must be considered when preparing for the pregnancy of these women.

Levels of thyroid-stimulating and thyroid hormones in pregnant women with obesity and their newborns

Aim: To study the level of thyroid-stimulating and thyroid hormones in pregnant women with obesity and their newborns.Materials and Methods. We consecutively recruited 40 pregnant women and their newborns. Blood sampling in pregnant women was carried out at the end of the third trimester 12 hours after the last meal while in newborns it was conducted immediately after birth. Measurement of serum thyroid-stimulating hormone, thyroxine, triiodothyronine, and free thyroxine was performed using chemiluminescent immunoassay.Results. Thyroid disease was significantly more common in pregnant women with obesity. Clinical and latent hypothyroidism in obese pregnant women was observed 1.5-fold more frequently as compared with those having normal body weight. In keeping with these findings, goiter and elevated thyroxine were also more common in obese pregnant women. Newborns from obese women were more often characterized by a transient hypothyroidism in combination with an augmented thyroid-stimulating hormone.Conclusion. Levels of thyroid-stimulating and thyroid hormones in obese pregnant women and their newborns significantly differ from the patients with normal body weight.

Evaluation the levels of thyroid hormones in pregnant women with phospholipid syndrome

Miscarriage in the early and late stages of pregnancy is a common problem in women with the anti-phospholipids syndrome. The current study aimed to determine the relationship between the syndrome of antibodies to phospholipid and thyroid hormones among pregnant women in the city of Nasiriyah. Blood samples were collected from (100) pregnant women with recurrent miscarriages due to phospholipid syndrome, the average aged (20-30) and (30-40) years. The results showed a significant increase in T3 and TSH hormones between ages (20-30), (30-40) years compared to the control group, as well as a significant increase in T4 hormone in pregnant women aged (20-30) while the ages group of (30-40) did not notice a significant change in the level of hormone T4 compared with the control group. We conclude that there is a relationship between thyroid hormones and autoimmune diseases.

Trimester-specific reference ranges for thyroid hormones in pregnant women.

The aim of this study was to determine the trimester-specific reference range of thyroid function in Nanjing.A total of 805 pregnant women in the 1st, 2nd, and 3rd trimesters were recruited in the prospective, observational study during their routine antenatal clinic visit and 282 nonpregnant subjects served as controls. A questionnaire was completed by the subjects to record their personal health history, family history of thyroid disease, and consumption of estrogen or antithyroid drugs. Thyroid palpation was performed to exclude the thyroid goiter. Thyroid function and urine iodine were measured by chemiluminescence and arsenic cerium analysis.The trimester-specific reference ranges in Nanjing were as follows: thyroid-stimulating hormone (TSH) 0.02 to 3.78 mIU/L, free thyroxine (FT4) 13.93 to 26.49 pmol/L, total thyroxine (TT4) 103.39 to 319.43 nmol/L in the 1st trimester. TSH 0.47 to 3.89 mIU/L, FT4 12.33 to 19.33 pmol/L, TT4 92.28 to 234.88 nmol/L in the 2nd trimester. TSH 0.55 to 4.91 mIU/L, FT4 11.38 to 19.21 pmol/L, TT4 83.54 to 258.12 nmol/L in the 3rd trimester. According to the TSH reference range recommended by American Thyroid Association (ATA), the prevalence of subclinical hypothyroidism, subclinical hyperthyroidism, hyperthyroidism, hypothyroxinemia, and thyroid peroxidase antibody-positive were 12.42%, 0.50%, 0.99%, 1.61%, and 11.80%, respectively, prevalence according to the trimester-specific reference range were 1.99%, 0.25%, 1.61%, 0.37%, and 1.61%, respectively, which showed elevated hypothyroxinemia incidence and declined incidence of subclinical hypothyroidism and hyperthyroidism.Trimester-specific reference range varied from that of ATA's recommendation, influencing the diagnosis, and treatment of pregnant thyroid disorders. To detect and control these disorders properly, setting up trimester-specific reference is clinically essential.

Associations of maternal exposure to triclosan, parabens, and other phenols with prenatal maternal and neonatal thyroid hormone levels

Environmental phenols and parabens are commonly used in personal care products and other consumer products and human exposure to these chemicals is widespread. Although human and animal studies suggest an association between exposure to phenols and parabens and thyroid hormone levels, few studies have investigated the association of in utero exposure to these chemicals and thyroid hormones in pregnant women and their neonates. We measured four environmental phenols (triclosan, benzophenone-3, and 2,4- and 2,5-dichlorophenol), and three parabens (methyl-, propyl-, and butyl paraben) in urine collected from mothers at two time points during pregnancy as part of the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study. We measured free thyroxine (T4), total T4, and thyroid-stimulating hormone (TSH) in serum of the pregnant women (N = 454) and TSH in their neonates (N = 365). We examined potential confounding by a large number of additional chemical exposures and used Bayesian Model Averaging (BMA) to select the most influential chemicals to include in regression models. We observed negative associations of prenatal urinary concentrations of propyl paraben and maternal TSH (β for two-fold increase = −3.26%, 95% CI: −5.55, −0.90) and negative associations of 2,4-dichlorophenol and maternal free T4 (β for two-fold increase = −0.05, 95% CI: −0.08, −0.02), after controlling for other chemical exposures. We observed negative associations of triclosan with maternal total T4 after controlling for demographic variables, but this association became non-significant after controlling for other chemicals (β for two-fold increase = −0.05, 95% CI: −0.11, 0.00). We found evidence that environmental phenols and parabens are associated with lower TSH and free T4 in pregnant women after controlling for related chemical exposures.

Association Between Organophosphate Pesticide Exposure and Thyroid Hormones in Pregnant Women.

Use of organophosphate pesticides (OPs) is widespread in China. Although animal studies suggested that OP exposure could affect thyroid function, little is explored in human populations. We investigated levels of OP exposure in pregnant women and the relationship between OPs and thyroid hormones in Shandong, China. We enrolled 637 pregnant women from April 2011 to December 2013. OP exposure was assessed by a questionnaire administered to the pregnant women in the hospital and by analyses of urinary dialkylphosphate (DAP) metabolites of OPs in pregnant women (n = 413). We measured the concentration of five thyroid hormones in serum samples in pregnant women (n = 325) and analyzed the association between DAP metabolites of OPs and thyroid hormones (n = 325). Median levels of DAP metabolites were 9.81 μg/L for dimethylphosphate (DMP), 0.79 μg/L for dimethylthiophosphate (DMTP), 5.00 μg/L for diethylphosphate (DEP), and 0.78 μg/L for diethylthiophosphate (DETP), which were higher than those reported in developed countries. We found that the total DAP concentration (the sum of DMP, DMTP, DEP, and DETP) in urine was positively associated with free T4 levels (β = 0.137; 95% confidence interval [CI] = 0.012, 0.263) and negatively associated with thyroid-stimulating hormone levels (β = -0.145; 95% CI = -0.242, -0.048). The findings suggest that OP exposure may be associated with changes in thyroid function in pregnant women. Given that urinary OP levels in pregnant women in Shandong were much higher than those reported in developed countries, further studies on the effects of OP exposure on thyroid function in pregnant women in China are warranted.

Reference intervals of thyroid hormones during pregnancy in Korea, an iodine-replete area

Background/AimsMaternal thyroid dysfunction has been associated with adverse pregnancy outcomes. The purpose of our study was to establish trimester-specific reference intervals for thyroid hormones in pregnant women in Korea, where iodine intake is more than adequate and to examine pregnancy and perinatal outcomes in their offspring.MethodsAmong 459 healthy pregnant women who were screened, we enrolled 417 subjects who had negative results for thyroid autoantibodies. Serum thyroid stimulating hormone (TSH) and free thyroxine were measured using an immunoradiometric assay. Urine iodine concentration was measured using inductively coupled plasma-mass spectrometry in 275 women. Reference ranges of thyroid hormones were determined according to the guidelines of the National Academy of Clinical Biochemistry. Pregnancy and perinatal outcomes were compared according to maternal thyroid function.ResultsThe reference ranges of serum TSH were 0.03 to 4.24 mIU/L in the first trimester, 0.13 to 4.84 mIU/L in the second trimester, and 0.30 to 5.57 mIU/L in the third trimester. Pregnancy and perinatal outcomes did not vary in mothers with subtle changes in thyroid function.ConclusionsTrimester-specific thyroid hormone reference intervals in Korean pregnant women differ from those of other countries with different iodine nutrition status and ethnicity. The establishment of population-based, reliable trimester-specific reference intervals is critical for the interpretation of thyroid function in pregnant women to avoid unnecessary tests and treatments.

Correlation of Serum 25-Hydroxyvitamin D and Thyroid Hormones in Pregnant Women in Amman-Jordan

1.1. Aim:The aim of this study is to investigate changes of vitamin D and thyroid hormones levels during pregnancy to maintain normal fetus development and growth. 1.2. Method: Serum hydroxyl vitamin 25(OH)D and thyroid levels were measured in109 pregnant women referred to our laboratory from prenatal clinic during the period of May to October 2015.Blood samples were detected for 25 (OH) vitamins D, TSH, FT4 and FT3by chemiluminescent(Tosoh A1A, Japan). 1.3. Results: Pregnant women aged 19-45years (18.2 years age average) were examined. The mean 25(OH) D was 21.7±5.6 ng/ml (range 8.7 to 47.2). The mean levels of Serum Free T3, FT4 and TSH were 1.61 ±0.21, ng/dl, 0.86 ±0.23 ng/dl and 1.56 ±.9 μIU/ml respectively, results for 25(OH) D mean values were 29.5 ng/ml (27.9%), 33.2 ng/ml (49.6%) and 37.3 ng/ml (22.5%) for vitamin D deficiency, insufficiency and sufficiency respectively. No correlation was found between vitamin D, TSH, FT4 and FT3 however, there was statistical significant correlation between the vitamin D and TSH (p<0.05), level especially in patients with sufficient vitamin D level. 1.4. Conclusion: Association between higher vitamin D (>30.0 ng/ml) and lower TSH in pregnant was observed (P<0.005). However, no correlation between 25-Hydroxyvitamin D FT4 and FT3 hormone was observed.

Exposure to phthalates during pregnancy and thyroid hormones in pregnant women and newborns

Introduction: Phthalates are endocrine disrupting chemicals found in many consumer products. Prior evidence suggests that some phthalates may disrupt thyroid function, but the effect of phthalates on thyroid hormones in pregnant women and neonates has not been thoroughly investigated. Methods: We measured nine phthalate metabolites representing exposure to six parent phthalate diesters in urine collected at ~16 and 26 weeks gestation in a prospective pregnancy and birth cohort. We calculated the mean of 16 and 26 week metabolite concentrations and created exposure quartiles. We measured thyroid stimulating hormone (TSH), free and total thyroxine (FT4, TT4), and triiodothyronine (FT3, TT3) concentrations in maternal serum at ~16 weeks (n=184) and in cord serum (n=275). We estimated the associations of phthalates with maternal or cord thyroid hormones by multivariable linear regression. Results: Mothers in the 4th quartile of urinary monoethyl phthalate (MEP) had 0.05 ng/dL lower FT4 (95%CI -0.09, -0.01) compared to those in the 1st quartile (p-trend=0.02). Cord TSH was 19.8% lower among infants born to women in the 4th quartile of monobenzyl phthalate (MBzP) (95%CI: -34.1, -2.3), compared to those in the 1st quartile (p-trend 0.03). Infants born to mothers in the 4th quartile of di(2-ethylhexyl) phthalate (DEHP) metabolites had decreased cord FT3 [-0.09 pg/mL (95%CI: -0.19, 0.01); p-trend=0.04] versus those in the 1st quartile. We observed marginally significant inverse trends of both MEP (p-trend=0.06) and monoisobutyl phthalate (MiBP) (p-trend=0.06) with cord TT4. Conclusions: In this cohort, maternal urinary MEP was inversely associated with maternal FT4. Maternal urinary concentrations of MBzP, DEHP metabolites, MEP, and MiBP were inversely associated with cord thyroid hormones. These results suggest that maternal exposure to phthalates during pregnancy may disrupt maternal and cord thyroid hormones necessary for normal growth and neurodevelopment.

Association between Pesticide Biomarkers and Reproductive and Thyroid Hormones in Pregnant Women

Introduction: Prenatal exposure to pesticides may be associated with health effects, including changes in maternal hormone levels that could potentially lead to adverse birth outcomes. The association of pesticides with reproductive and thyroid hormones were examined in the first 44 pregnant women (86 observations) recruited for a large prospective cohort study in Puerto Rico. Methods: Serum hormone levels (estrogen, progesterone, sex hormone-binding globulin (SHBG), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH)) and urinary pesticide biomarkers (parathion, a pyrethyroid metabolite, three DEET metabolites, and five organophospohate (OP) metabolites) were measured at two visits during pregnancy (16-20 and 24-28 weeks). We used linear mixed models with a random intercept to examine associations between the exposure biomarkers and hormones, adjusting for specific gravity, visit, maternal age, BMI and education. All pesticide biomarkers, progesterone and TSH were log-transformed. Results: The only significant association among reproductive hormones was a 9.13% increase (95% CI 2.90, 15.36) in SHBG with an IQR increase in diethylthiophosphate (OP metabolite). An IQR increase across all DEET metabolites (3-(diethylcarbamoyl)benzoic acid (DCBA), N-ethyl-3-methyl-benzamide and N,N-diethyl-3-(hydroxymethyl)benzamide) was associated with a 5.45% (95% CI -10.61, -0.29), 3.32% (95% CI -6.36, -0.28) and 1.66% (95% CI -3.67, 0.35) decrease in FT3, respectively. The results also suggested a 15.90% (95% CI -1.48, 36.33) and a 19.64% (95% CI -2.60, 46.97) increase in TSH with an IQR increase in DCBA and the pyrethroid metabolite, respectively. Conversely, a 9.16% decrease (95% CI -18.19, 0.86) in TSH was observed with an IQR increase in dimethyldithiophosphate (OP metabolite). Conclusions: In this exploratory study, pyrethroid, DEET and OP were associated with SHBG, TSH and FT3 which may potentially lead to adverse health effects.

Phenols and parabens in relation to reproductive and thyroid hormones in pregnant women

IntroductionPhenols and parabens are ubiquitous environmental contaminants. Evidence from animal studies and limited human data suggest they may be endocrine disruptors. In the current study, we examined associations of phenols and parabens with reproductive and thyroid hormones in 106 pregnant women recruited for the prospective cohort, “Puerto Rico Testsite for Exploring Contamination Threats (PROTECT)”. MethodsUrinary exposure biomarkers (bisphenol A, triclosan, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, butyl, methyl and propyl paraben) and serum hormone levels (estradiol, progesterone, sex hormone-binding globulin (SHBG), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone) were measured at up to two time points during pregnancy (16–20 weeks and 24–28 weeks). We used linear mixed models to assess relationships between exposure biomarkers and hormone levels across pregnancy, controlling for urinary specific gravity, maternal age, BMI and education. In sensitivity analyses, we evaluated cross-sectional relationships between exposure and hormone levels stratified by study visit using linear regression. ResultsAn IQR increase in methyl paraben was associated with a 7.70% increase (95% CI 1.50, 13.90) in SHBG. Furthermore, an IQR increase in butyl paraben as associated with an 8.46% decrease (95% CI 16.92, 0.00) in estradiol, as well as a 9.34% decrease (95% CI −18.31,−0.38) in estradiol/progesterone. Conversely, an IQR increase in butyl paraben was associated with a 5.64% increase (95% CI 1.26, 10.02) in FT4. Progesterone was consistently negatively associated with phenols, but none reached statistical significance. After stratification, methyl and propyl paraben were suggestively negatively associated with estradiol at the first time point (16–20 weeks), and suggestively positively associated with estradiol at the second time point (24–28 weeks). ConclusionsWithin this ongoing birth cohort, certain phenols and parabens were associated with altered reproductive and thyroid hormone levels during pregnancy. These changes may contribute to adverse health effects in mothers or their offspring, but additional research is required.

Maternal phthalate exposure during the first trimester and serum thyroid hormones in pregnant women and their newborns

Animal and human studies have suggested that phthalate alters thyroid hormone concentrations. This study investigated the associations between phthalate exposure during the first trimester and thyroid hormones in pregnant women and their newborns. Pregnant women were enrolled from the prospective Ma’anshan Birth Cohort study in China. A standard questionnaire was completed by the women at the first antenatal visit. Seven phthalate metabolites were measured in one-spot urine at enrolment (10.0 ± 2.1 gestational weeks), as were thyroid hormone levels in maternal and cord sera. Multivariable linear regression showed that 1-standard deviation (SD) increase in natural log (ln)-transformed mono(2-ethylhexyl) phthalate (MEHP) and mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was associated with 0.163 μg/dL (p = 0.001) and 0.173 μg/dL (p = 0.001) decreases in maternal total thyroxine (TT4). Both MEHP and MEHHP were negatively associated with maternal free thyroxine (FT4; β: −0.013, p < 0.001 and β: −0.011, p = 0.001, respectively) and positively associated with maternal thyroid-stimulating hormone (β: 0.101, p < 0.001; β: 0.132, p < 0.001, respectively). An inverse association was observed between monobenzyl phthalate and maternal TT4 and FT4. A 1-SD increase in ln-transformed monoethyl phthalate was inversely associated with maternal TT4 (β: −0.151, p = 0.002). By contrast, the concentrations of phthalate metabolites in urine were not associated with those of thyroid hormone in cord serum. Our analysis suggested that phthalate exposure during the first trimester disrupts maternal thyroid hormone levels.

Associations between Repeated Measures of Maternal Urinary Phthalate Metabolites and Thyroid Hormone Parameters during Pregnancy.

Background:Maintaining thyroid homeostasis during pregnancy is essential for normal fetal growth and development. Growing evidence suggests that phthalates interfere with normal thyroid function. Few human studies have investigated the degree to which phthalates may affect thyroid hormone levels in particularly susceptible populations such as pregnant women.Objectives:We examined the associations between repeated measures of urinary phthalate metabolites and plasma thyroid hormone levels in samples collected at up to four time points per subject in pregnancy. Additionally, we investigated the potential windows of susceptibility to thyroid hormone disturbances related to study visit of sample collection.Methods:Data were obtained from pregnant women (n = 439) participating in a nested case–control study of preterm birth with 116 cases and 323 controls. We measured 9 phthalate metabolite concentrations in urine samples collected at up to four study visits per subject during pregnancy (median = 10, 18, 26, and 35 weeks of gestation, respectively). We also measured a panel of thyroid function markers in plasma collected at the same four time points per subject during pregnancy.Results:Although our results were generally null, in repeated measures analyses we observed that phthalate metabolites were largely inversely associated with thyrotropin and positively associated with free and total thyroid hormones. Cross-sectional analyses by study visit revealed that the magnitude and/or direction of these relationships varied by timing of exposure during gestation.Conclusions:These results support previous reports showing the potential for environmental phthalate exposure to alter circulating levels of thyroid hormones in pregnant women.Citation:Johns LE, Ferguson KK, McElrath TF, Mukherjee B, Meeker JD. 2016. Associations between repeated measures of maternal urinary phthalate metabolites and thyroid hormone parameters during pregnancy. Environ Health Perspect 124:1808–1815; http://dx.doi.org/10.1289/EHP170