Obstetric management of thyroid disease

A new prognostic model for recurrent pregnancy loss: assessment of thyroid and thromboelastograph parameters

Objective

This study aimed to identify predictors associated with thyroid function and thromboelastograph (TEG) examination parameters and establish a nomogram for predicting the risk of subsequent pregnancy loss in recurrent pregnancy loss (RPL).

Methods

In this retrospective study, we analyzed the medical records of 575 RPL patients treated at Lanzhou University Second Hospital, China, between September 2020 and December 2022, as a training cohort. We also included 272 RPL patients from Ruian People's Hospital between January 2020 and July 2022 as external validation cohort. Predictors included pre-pregnancy thyroid function and TEG examination parameters. The study outcome was pregnancy loss before 24 weeks of gestation. Variable selection was performed using least absolute shrinkage and selection operator regression and stepwise regression analyses, and the prediction model was developed using multivariable logistic regression. The study evaluated the model's performance using the area under the curve (AUC), calibration curve, and decision curve analysis. Additionally, dynamic and static nomograms were constructed to provide a visual representation of the models.

Results

The predictors used to develop the model were body mass index, previous pregnancy losses, triiodothyronine, free thyroxine, thyroid stimulating hormone, lysis at 30 minutes, and estimated percent lysis which were determined by the multivariable logistic regression with the minimum Akaike information criterion of 605.1. The model demonstrated good discrimination with an AUC of 0.767 (95%CI 0.725-0.808), and the Hosmer-Lemeshow test indicated good fitness of the predicting variables with a P value of 0.491. Identically, external validation confirmed that the model exhibited good performance with an AUC of 0.738. Moreover, the clinical decision curve showed a positive net benefit in the prediction model. Meanwhile, the web version we created was easy to use. The risk stratification indicated that high-risk patients with a risk score >147.9 had a higher chance of pregnancy loss (OR=6.05, 95%CI 4.09-8.97).

Conclusions

This nomogram well-predicted the risk of future pregnancy loss in RPL and can be used by clinicians to identify high-risk patients and provide a reference for pregnancy management of RPL.

Prenatal Maternal Low Selenium, High Thyrotropin, and Low Birth Weights

In consideration of the potential roles of selenoproteins in thyroid function, we aimed to evaluate the association of low selenium status with hypothyroidism during pregnancy and the association of maternal low thyroid function with infant birth size. We conducted a prospective birth cohort study in Shanghai in 2010 and investigated 1931 pregnant mothers of gestational weeks 28-36. Maternal serum selenium and thyrotropin (TSH) levels were determined and birth weights and lengths of newborns were measured. Other covariates were obtained through maternal interviews and medical records. A non-linear association was observed between maternal selenium and TSH levels. Two-piecewise multivariable linear regression models were therefore applied to assess the association of serum selenium with TSH levels, and multivariable linear regression models were applied to assess the association of TSH levels with birth weight/length. Adjusting for potential confounders, when maternal serum selenium levels < 103.7 μg/L (P25th), each unit increase in selenium levels (μg/L) was significantly associated with a decrease of 0.014 μIU/mL in TSH levels (β = - 0.014, 95%CI - 0.025, - 0.002, P = 0.023). However, when selenium levels ≥ 103.7 μg/L, there were no significant relationships between selenium and TSH (β = 0.000, 95%CI - 0.001, 0.002, P = 0.859). Maternal TSH levels were significantly inversely associated with infant birth weight (β = - 0.060, 95%CI - 0.100, - 0.010, P = 0.010). We observed a non-linear association between maternal selenium status and TSH levels. Low selenium status during pregnancy may associate with low thyroid function that was related with low birth weights. Graphical abstract .

Endocrine Emergencies in Obstetrics

Endocrine emergencies in pregnancy can be life threatening and are associated with increased morbidity for both the mother and fetus. Thyroid storm, diabetic ketoacidosis, and hypercalcemic crisis require a high clinical suspicion, rapid treatment, and multidisciplinary care to ensure best outcomes. Critical care consultation and intensive care unit admission are often warranted. Fetal testing may initially be concerning; however often improves with correction of the underlying metabolic derangement(s) and delivery is generally avoided until maternal status improves.

Case Studies in Thyroid Dysfunction and Pregnancy

This chapter represents a selection of 8 clinical scenarios that may commonly be encountered. They help summarize some of the literature and teaching points of the previous chapters. They are not meant to represent every possible presentation of thyroid disease, but rather to present common symptoms and findings that may aid a clinician in making a diagnosis or in selecting initial treatment.

Maternal TSH levels at first trimester and subsequent spontaneous miscarriage: a nested case-control study

Thyroid dysfunction is a frequently found endocrine disorder among reproductively aged women. Subclinical hypothyroidism is the most common condition of thyroid disorders during pregnancy and is defined as manifesting a thyroid-stimulating hormone concentration exceeding the trimester-specific reference value, with a normal free thyroxine concentration. Here, we evaluated the prospective association between spontaneous miscarriage and first-trimester thyroid function. We conducted a case-control study (421 cases and 1684 controls) that was nested. Thyroid-stimulating hormone (TSH), free thyroxine (FT4), thyroid-peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) status were measured. We found that higher TSH was related to spontaneous miscarriage (OR 1.21; 95% CI, 1.13-1.30, P < 0.001). Compared with women with TSH levels of 0.4-<2.5 mIU/L, the risk of miscarriage was increased in women with TSH levels of 2.5-<4.87 mIU/L (OR 1.47; 95% CI, 1.16-1.87) and TSH greater than 4.87 mIU/L (OR 1.97; 95% CI, 1.22-3.18). After controlling for the confounding factor, TPOAb positivity status and FT4, the results were similar. The present study showed that higher TSH was associated with miscarriage in early pregnancy. In fact, TSH levels between 2.5 and 4.87 mIU/L increased the risk for miscarriage, with TSH greater than 4.87 mIU/L increasing the risk even further.

Effect of mildly elevated thyroid-stimulating hormone during the first trimester on adverse pregnancy outcomes

BACKGROUND

To investigate the effect of a mildly elevated thyroid-stimulating hormone (TSH) concentration between 2.5 and 4.0 mIU/L during the first trimester on pregnancy outcomes in thyroid peroxydase antibody (TPOAb)-negative pregnant women.

METHODS

A total of 1858 pregnant women who were TPOAb-negative before 13^+ 6 gestational weeks, received regular prenatal services, and delivered in the third affiliated hospital of Sun Yat-Sen University were recruited from June 2016 to June 2017. Measurements of thyroid function (TSH, free T4 [FT4] and TPOAb) and adverse pregnancy outcomes were assessed and recorded.

RESULTS

Among the 1858 study participants, the 97.5th percentile for TSH was 3.76 mIU/L, and 142 women (7.6%) had mildly elevated TSH levels between 2.5 and 4.0 mIU/L. No differences in the incidence of adverse pregnancy outcomes were observed between patients with a mildly elevated TSH level and those with a normal TSH level (< 2.5 mIU/L).

CONCLUSION

A mildly elevated TSH concentration (2.5-4.0 mIU/L) during the first trimester of pregnancy in TPOAb-negative women was not associated with adverse pregnancy outcomes in our study population. Accordingly, it may be possible to raise the upper limit of the healthy TSH reference range for pregnant women.

Impending thyroid storm in a pregnant woman with undiagnosed hyperthyroidism: A case report and literature review

RATIONALE

Thyroid storm is a rare complication during caesarean section of patients with hyperthyroidism. It occurs abruptly, with a high mortality rate if not recognized immediately and aggressively treated. Herein, we reported a case of impending thyroid storm during a caesarean section.

PATIENT CONCERNS

A healthy 23-year-old woman with undiagnosed hyperthyroidism underwent an emergency caesarean section under general anesthesia. After tracheal extubation, the patient exhibited abnormal tachycardia, agitation, sweating, and hyperpyrexia.

DIAGNOSES

The clinical manifestation and the following thyroid function test indicate a high index of suspicion for impending thyroid storm.

INTERVENTIONS

Hydrocortisone and esmolol were intravenously administered immediately. Propylthiouracil and propranolol were orally administered after the patient regained complete consciousness.

OUTCOMES

Due to our immediate recognition and aggressive treatment, more serious manifestations of thyroid storm were avoided.

LESSONS

Good antenatal care is very important for pregnant women, and they should be generally screened for thyroid disorders, especially if the resting heart rate is >100 beats/min and weight increases are inconsistent with gestational age. When hyperthyroidism is suspected, drugs that excite the sympathetic nerves or promote the release of histamine should not be used during caesarean section.

Effect of gestational subclinical hypothyroidism on early neurodevelopment of offspring

OBJECTIVE

To evaluate the effects of gestational subclinical hypothyroidism (SCH) on early neurodevelopment of offspring.

STUDY DESIGN

A prospective study included 106 infants born to mothers with gestational SCH and 106 infants born to mothers who were euthyroid during pregnancy. The neurodevelopment of 12 to 24-month-old infants was assessed and compared using the Gesell developmental test (revised version).

RESULTS

Infants born to mothers with gestational SCH and those born to euthyroid mothers had similar scores on the Gesell development test. No correlations were observed between maternal TSH concentration and Gesell developmental test scores of offspring. Infants born to mothers who had gestational SCH during the first trimester specifically and those born to euthyroid mothers had similar scores on the Gesell development test. No significant correlations were detected between maternal TSH concentration during the first trimester and offspring neurodevelopment.

CONCLUSIONS

No detectable neurodevelopment deficit was observed in offspring up to 24 months old from mothers who had gestational SCH.

Effects of subclinical hypothyroidism on maternal and perinatal outcomes during pregnancy: a single-center cohort study of a Chinese population

OBJECTIVE

Adverse maternal outcomes and perinatal complications are closely associated with overt maternal hypothyroidism, but whether these complications occur in women with subclinical hypothyroidism (SCH) during pregnancy remains controversial. The aim of this study was to evaluate the effects of SCH on maternal and perinatal outcomes during pregnancy.

METHODS

A prospective study of data from 8012 pregnant women (371 women with SCH, 7641 euthyroid women) was performed. Maternal serum samples were collected in different trimesters to examine thyroid hormone concentrations. SCH was defined as a thyroid stimulating hormone concentration exceeding the trimester-specific reference value with a normal free thyroxine concentration. The occurrence of maternal outcomes, including gestational hypertension (GH), gestational diabetes mellitus, placenta previa, placental abruption, prelabor rupture of membranes (PROM), and premature delivery; and perinatal outcomes, including intrauterine growth restriction (IUGR), fetal distress, low birth weight (LBW; live birth weight ≤ 2500 g), stillbirth, and malformation, was recorded. Logistic regression with adjustment for confounding demographic and medical factors was used to determine the risks of adverse outcomes in patients with SCH.

RESULTS

Compared with euthyroid status, SCH was associated with higher rates of GH (1.819% vs. 3.504%, P = 0.020; χ2 = 7.345; odds ratio (OR), 2.243; 95% confidence interval (CI), 1.251-4.024), PROM (4.973% vs. 8.625%, P = 0.002; χ2 = 72.102; adjusted OR, 6.014; 95% CI, 3.975-9.099), IUGR (1.008% vs. 2.965%, <0.001; χ2 = 13.272; adjusted OR, 3.336; 95% CI, 1.745-6.377), and LBW (1.885% vs. 4.582%, P<0.001; χ2 = 13.558; adjusted OR, 2.919; 95% CI, 1.650-5.163).

CONCLUSIONS

The results of this study indicate that pregnant women with SCH had increased risks of GH and PROM, and their fetuses and infants had increased risks of IUGR and LBW. Thus, routine maternal thyroid function testing is necessary to improve maternal and perinatal outcomes.

The safety of methimazole and propylthiouracil in pregnancy: a systematic review

BACKGROUND

Hyperthyroidism is one of the most common endocrine disorders in pregnant women, and it can severely complicate the course and outcome of pregnancy. Methimazole (MMI) and propylthiouracil (PTU) are the standard anti-thyroid drugs used in the treatment of hyperthyroidism in pregnancy. Traditionally, MMI has been considered to have clearer evidence of teratogenicity than PTU. Recent studies suggest that PTU can be hepatotoxic, leading to a United States Food and Drug Administration "black box alert." We wished to systematically review the effects of PTU and MMI during pregnancy, and to compare maternal and fetal safety.

METHODS

We conducted a systematic search of PubMed, EMBASE, TOXNET, TOXLINK, DART, Medscape, EBSCO, and Google. Both English and non-English publications were included. We excluded studies using anti-thyroid therapies other than PTU and MMI, studies not allowing interpretation of results, and abstracts of meetings.

RESULTS

Overall, insufficient statistical power precluded determination of accurate rates of either MMI teratogenicity or PTU hepatotoxicity in cohort studies. However, a case-control study helped identify the relative risk of MMI-induced choanal atresia. A second case-control study failed to show that aplasia cutis congenita is associated with MMI. PTU has been associated with a rare but serious form of hepatic failure.

CONCLUSION

MMI causes a specific pattern of rare teratogenic effects after first trimester exposure, while PTU therapy may be followed by rare but severe hepatotoxic sequelae. It is therefore appropriate to use PTU to treat maternal hyperthyroidism during the first trimester of pregnancy, and to switch to MMI for the remainder of the pregnancy.

Endocrine emergencies

Several potentially fatal endocrine emergencies in relation to obstetrics and gynecology are discussed in the article. Rates of case fatality vary in different series, but range from 10% to 30%. Rapid recognition, prompt supportive care, and intervention likely maximize maternal and fetal outcomes.

Subclinical hypothyroidism in pregnancy: intellectual development of offspring

BACKGROUND

The effects of maternal subclinical hypothyroidism (M-SCH) on the neuropsychological development of the offspring are not clear. We evaluated the intellectual development of children of mothers who had M-SCH during the pregnancy for these children.

METHODS

Sixty-two children were recruited. After excluding those age < 4 or age > 15, 44 were enrolled. The mothers of these children were part of a sub-pool of 90, of 441 hypothyroid women of reproductive age seen in Tehran endocrine clinics between 1991 and 2003 and who were observed during gestation. Mothers were receiving levothyroxine (LT4) before gestation. Mothers of 19 children (control group) had normal serum thyrotropin (TSH) during the pregnancy that produced these children. Mothers of the other 25 children had increased TSH during the comparable pregnancy. Nineteen mothers had M-SCH (case group) and six had overt hypothyroidism. Serum TSH and free T4 (FT4) and urine iodine were measured, and seven cognitive performance and intelligence quotient (IQ) tests were performed.

RESULTS

Case children were similar to control children with respect to gender, age, parental education, maternal age at time of pregnancy and at the time of their hypothyroidism, percent mothers having thyroid peroxidase antibodies, LT4 dose of mothers during pregnancy, gestational age at delivery, birth weight, and duration of breast feeding. Maternal TSH (mean ± standard deviation) in the case group during their mother's pregnancies was 11.3 ± 5.3 and 1.4 ± 1.0 mU/L in the controls (p < 0.001). Serum TSH, FT4 and urinary iodine concentrations were similar in the two groups. Total IQ, performance IQ, and verbal IQ were similar, being 120 ± 14, 117 ± 12, and 121 ± 16, respectively, in the case group and 121 ± 11, 120 ± 7, and 117 ± 15 in the control group. Cognitive performance tests were similar in both groups. No relationships were observed between variables and IQ except for education level of the mother and neonatal weight.

CONCLUSION

IQ level and cognitive performance of children born to LT4-treated hypothyroid mothers is similar in those whose mothers have M-SCH during pregnancy compared with those whose mothers have normal serum TSH concentrations during pregnancy.

Overt and subclinical thyroid dysfunction among Indian pregnant women and its effect on maternal and fetal outcome

PURPOSE

Thyroid disorders are among the common endocrine problems in pregnant women. It is now well established that not only overt, but subclinical thyroid dysfunction also has adverse effects on maternal and fetal outcome. There are few data from India about the prevalence of thyroid dysfunction in pregnancy. With this background, this study aims to find prevalence of thyroid dysfunction in pregnancy and its impact on obstetrical outcome in Indian population.

METHODS

Six hundred and 33 pregnant women in second trimester were registered. Detailed history and examination was done. Apart from routine obstetrical investigations, TSH level estimation was done. If TSH level was deranged then free T4 and thyroperoxidase antibody level estimation were done. Patients were managed accordingly and followed till delivery. Their obstetrical and perinatal outcomes were noted.

RESULTS

Prevalence of thyroid dysfunction was high in this study, with subclinical hypothyroidism in 6.47% and overt hypothyroidism in 4.58% women. Overt hypothyroids were prone to have pregnancy-induced hypertension (P=0.04), intrauterine growth restriction (P=0.01) and intrauterine demise (P=0.0004) as compared to control. Cesarean section rate for fetal distress was significantly higher among pregnant subclinical hypothyroid women (P=0.04). Neonatal complications and gestational diabetes were significantly more in overt hyperthyroidism group (P=0.03 and P=0.04, respectively).

CONCLUSIONS

Prevalence of thyroid disorders, especially overt and subclinical hypothyroidism (6.47%) was high. Significant adverse effects on maternal and fetal outcome were seen emphasizing the importance of routine antenatal thyroid screening.

Use of oral contraceptives, intrauterine devices and tubal sterilization and cancer risk in a large prospective study, from 1996 to 2006

The association of contraceptive methods, including oral contraceptives (OC), intrauterine devices (IUD) and tubal sterilization (TS), with overall and site-specific cancer were prospectively investigated in a cohort of 66,661 Chinese women in Shanghai, 76.7% of whom used contraception. During a median follow-up time of 7.5 years, 2,250 women were diagnosed with cancer. Ever-use of any contraceptive method was not associated with overall cancer risk [adjusted hazard ratio (HR(adj)) = 1.02, 95% CI, 0.92-1.12]. Use of any contraceptive method was associated with increased risk of rectal cancer (HR(adj) = 1.68, 95% CI, 1.08-2.62) and reduced risk of thyroid cancer (HR(adj) = 0.63, 95% CI, 0.38-1.04). Risk of gallbladder cancer increased with ever use of OC (HR(adj) = 2.38, 95% CI, 1.26-4.49). IUD use was associated with a possible reduced risk of thyroid cancer (HR(adj) = 0.64, 95% CI, 0.38-1.07). Longer duration of IUD use decreased risk for breast, thyroid and lung cancers. Ever having a TS was associated with increased uterine body cancer (HR(adj) = 2.50, 95% CI, 1.47-4.25) and decreased risk of stomach cancer (HR(adj) = 0.59, 95% CI, 0.39-0.91). We did not find any contraceptive method to be related to the risk of ovarian cancer but the analyses were based on few events. Although chance findings are a likely explanation for some of the associations found in our study, these findings suggest that various contraceptive methods or reproductive patterns may play a role in the etiology of cancer.

Autoimmune disease during pregnancy and the microchimerism legacy of pregnancy

Pregnancy has both short-term effects and long-term consequences on the maternal immune system. For women who have an autoimmune disease and subsequently become pregnant, pregnancy can induce amelioration of the mother's disease, such as in rheumatoid arthritis, while exacerbating or having no effect on other autoimmune diseases like systemic lupus erythematosus. That pregnancy also leaves a long-term legacy has recently become apparent by the discovery that bi-directional cell trafficking results in persistence of fetal cells in the mother and of maternal cells in her offspring for decades after birth. The long-term persistence of a small number of cells (or DNA) from a genetically disparate individual is referred to as microchimerism. While microchimerism is common in healthy individuals and is likely to have health benefits, microchimerism has been implicated in some autoimmune diseases such as systemic sclerosis. In this paper, we will first discuss short-term effects of pregnancy on women with autoimmune disease. Pregnancy-associated changes will be reviewed for selected autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus and autoimmune thyroid disease. The pregnancy-induced amelioration of rheumatoid arthritis presents a window of opportunity for insights into both immunological mechanisms of fetal-maternal tolerance and pathogenic mechanisms in autoimmunity. A mechanistic hypothesis for the pregnancy-induced amelioration of rheumatoid arthritis will be described. We will then discuss the legacy of maternal-fetal cell transfer from the perspective of autoimmune diseases. Fetal and maternal microchimerism will be reviewed with a focus on systemic sclerosis (scleroderma), autoimmune thyroid disease, neonatal lupus and type I diabetes mellitus.