Effects of increasing levothyroxine on pregnancy outcomes in women with uncontrolled hypothyroidism

Development, Validation and Clinical Utility of a Risk Prediction Model for Maternal and Neonatal Adverse Outcomes in Pregnant Women with Hypothyroidism

Purpose

This study aimed to create, verify and assess the clinical utility of a prediction model for maternal and neonatal adverse outcomes in pregnant women with hypothyroidism.

Methods

A prediction model was developed, and its accuracy was tested using data from a retrospective cohort. The study focused exclusively on female patients diagnosed with hypothyroidism who were admitted to a tertiary hospital. The development and validation cohort comprised individuals who gave birth between 1 October 2020 and 31 December 2022. The primary outcome was a combination of crucial maternal and newborn problems (eg premature births, abortions and neonatal asphyxia). The prediction model was developed using logistic regression. Evaluation of the model's performance was conducted based on its ability to discriminate, calibrate and provide clinical value.

Results

In total, nine variables were chosen to develop the predictive model for adverse maternal and neonatal outcomes during pregnancy with hypothyroidism. The area under the curve of the model for predicting maternal adverse outcomes was 0.845, and that for predicting neonatal adverse outcomes was 0.685. The calibration plots showed good agreement between the nomogram predictions and the actual observations in both the training and validation cohorts. Furthermore, decision curve analysis suggested that the nomograms were clinically useful and had good discriminative power to identify high-risk mother-infant cases.

Conclusion

Two models to predict the risk probability of maternal and neonatal adverse outcomes in pregnant women with hypothyroidism were developed and verified to assist physicians in evaluating maternal and neonatal adverse outcomes throughout pregnancy with hypothyroidism and to facilitate decision-making regarding therapy.

Levothyroxine dosages during pregnancy among hypothyroid women. An experience from a tertiary care center of Karachi, Pakistan, based on data from Maternal Hypothyroidism on Pregnancy Outcomes Study (MHPO-5)

Objectives

The dosage of levothyroxine (LT4) during pregnancy differs among different ethnic groups worldwide. These differences are due to variations in geographical iodine distribution, autoimmunity, and variations in thyrotropin (TSH) targets for pregnancy. To the best of our knowledge, we report the levothyroxine dosage prescribed during pregnancy in hypothyroid women, for the first time from Pakistan.

Results

Levothyroxine dosage of 280 hypothyroid women during pregnancy were reviewed. The median LT4 dosages prescribed before conception was 85.7 mcg per day which increased by 14.3 mcg per day in the first trimester (P 0.001). A significant difference in dosage was observed between controlled and uncontrolled TSH groups in the first trimester (P 0.05). Lower LT4 dosage was prescribed for subclinical hypothyroid women as compared to overt hypothyroid cases, whereas dosages did not differ according to autoimmune status in the latter part of gestation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-05984-7.

Thyroid Laboratory Testing and Management in Women on Thyroid Replacement Before Pregnancy and Associated Pregnancy Outcomes

Background: Women with hypothyroidism before pregnancy often require an increase in their levothyroxine dosage to maintain a euthyroid state during pregnancy. The objectives of this study were to investigate: (i) the frequency and distribution of thyrotropin (TSH) testing and levothyroxine dosage adjustment by gestational age, (ii) the magnitude of levothyroxine increase by the underlying etiology of hypothyroidism, and (iii) the relationship of overtreatment or undertreatment during pregnancy with adverse pregnancy outcomes among women using thyroid replacement before pregnancy. Methods: A retrospective cohort study of pregnancies in women on thyroid replacement before pregnancy in Alberta, Canada, was performed. Women using thyroid replacement anytime during the two years before pregnancy who delivered between October 2014 and September 2017 were included. Delivery records, physician billing, and laboratory and pharmacy administrative data were linked. Outcomes included characteristics of TSH testing, levothyroxine dosing, and pregnancy outcomes. The frequency and gestational timing of TSH testing and levothyroxine adjustments were calculated. Multiple logistic regression was used to test whether pregnancies with TSH <0.10 mIU/L (overtreatment) or TSH ≥10.00 mIU/L (undertreatment) compared with control pregnancies (TSH 0.10-4.00 mIU/L) were associated with adverse pregnancy and neonatal outcomes. Results: Of the 10,680 deliveries, 8774 (82.2%) underwent TSH testing at least once during pregnancy, at a median gestational age of six weeks. An adjustment of levothyroxine dosage was made for 4321 (43.7%) during pregnancy. TSH in pregnancy below 0.10 mIU/L increased the odds of preterm delivery when compared with control pregnancies (adjusted odds ratio, 2.14 [95% confidence interval 1.51-2.78]). TSH ≥10.00 mIU/L during pregnancy was not associated with any adverse pregnancy or neonatal outcomes in the multivariable analysis. Conclusions: Although most women on thyroid replacement before conception had TSH measured at some point during pregnancy, it is concerning that 17.8% did not. Levothyroxine overtreatment in pregnancy was associated with preterm delivery. These findings suggest that clinicians should be careful to avoid overtreatment with levothyroxine in pregnancy.

Knowledge, Attitudes, Beliefs, and Treatment Burden Related to the Use of Levothyroxine in Hypothyroid Pregnant Women in the United States

Background: The use of prescribed medications during pregnancy is a challenge and an underestimated source of treatment burden. Levothyroxine (LT4) for the treatment of overt and subclinical hypothyroidism is extensively prescribed during pregnancy. To this end, we aimed to explore the patients' perceived benefits and risks, knowledge, beliefs, attitudes, and related burden of LT4 therapy during pregnancy. Methods: In this cross-sectional study, we surveyed pregnant women who were treated with LT4 during pregnancy from January 1, 2019, to December 31, 2019, in a tertiary academic medical center of the United States. The anonymous online survey included questions to gather demographic data and multiple-choice questions regarding the benefits and risks, knowledge, beliefs, attitudes, and burden related to LT4 use during pregnancy. Results: Sixty-four pregnant women (mean age 31.5 years) completed the study survey (response rate: 96%): 62% were diagnosed with hypothyroidism more than 12 months before pregnancy, 16% less than or about 12 months before pregnancy, and 22% during pregnancy. We found that one-third of pregnant women using LT4 had a feeling of uneasiness/anxiety due to their hypothyroidism diagnosis. About half of the respondents (45%) reported that they did not receive an explanation by their clinician regarding the maternal/fetal risks of uncontrolled hypothyroidism or the benefits of adequate control. Finally, two in three patients expressed various concerns of LT4-related treatment burden. Conclusions: Our findings support the need for increased effective communication and tailored counseling to address fears, anxiety, and uncertainties about the benefits and risks of LT4 use in pregnancy. For patients with clear benefits from LT4 treatment in pregnancy, it could help to overcome their concerns, promote adherence, and decrease adverse maternal/fetal outcomes. For patients with no clear benefits established, clinicians need to be aware of LT4-related treatment burden in pregnancy and implement patient-centered approaches in their clinical practices.

Neonatal outcome in pregnancy hypotiroidee women

To evaluate the impact that hypothyroidism may have on the course of pregnancy and on neonatal outcome. This cross-sectional study consisting of 160 pregnant women (60 with hypothyroidism and 100 as control) who had been hospitalized at the Obstetrics and Gynecology of the University of Siena. The obstetric visit, the collection of anamnestic data and serum concentrations of TSH, FT4 and AbTPO were performed for each woman. Stratification of the population into two groups based on the BMI showed that there is an average difference of -0.88 before pregnancy BMI between healthy women and hypothyroid women. Moreover, with regard to the obstetric history, 8.7 times higher risk of abortion was found in hypothyroid women. About the current pregnancy in hypothyroid women, slight fetal growth delay, increased risk of premature rupture of membranes (PROM), and a higher risk of developing hypertension and gestational diabetes had been found. The importance of a more detailed anamnesis should be evaluated with greater attention at the beginning of pregnancy. This, in order to avoid the risks related to a hypothyroidism condition during pregnancy and to establish an early therapeutic treatment appropriate to the metabolic demands of each patient.

Thyroid hormone therapy of hypothyroidism in pregnancy

Hypothyroidism is the most frequent pregnancy-related thyroid dysfunction, including overt and subclinical hypothyroidism. Studies show that even mild hypothyroidism may eventuate in adverse gestational outcomes and intellectual impairment of offspring. Women with overt hypothyroidism (OH) must be treated by levothyroxine (LT4) pre- and during pregnancy, however, it is controversial that when and how to initiate LT4 therapy and further optimize dosing so that pregnant women and their offspring may truly benefit. In the review we will analyze the changes in thyroid hormone requirements in pregnant women, the timing of LT4 treatment and adjustment of LT4 dose according to etiology in patients with hypothyroidism during pregnancy, and adjustment of LT4 after delivery.

Pregnancy outcomes are not altered by variation in thyroid function within the normal range in women free of thyroid disease

OBJECTIVE

In the recently revised guidelines on the management of thyroid dysfunction during pregnancy, treatment with thyroid hormone (LT4) is not recommended in women without thyroid autoimmunity (TAI) and TSH levels in the range 2.5-4.0 mIU/L, and in a recent study in that particular group of pregnant women, more complications were observed when a treatment with LT4 was given. The objective of the study was therefore to investigate whether variation in thyroid function within the normal (non-pregnant) range in women free of thyroid disease was associated with altered pregnancy outcomes?

DESIGN

Cross-sectional data analysis of 1321 pregnant women nested within an ongoing prospective collection of pregnant women's data in a single centre in Brussels, Belgium.

METHODS

Thyroid peroxidase antibodies (TPO-abs), thyroid-stimulating hormone (TSH), free T4 (FT4) and ferritin levels were measured and baseline characteristics were recorded. Women taking LT4, with TAI and thyroid function outside the normal non-pregnant range were excluded. Pregnancy outcomes and baseline characteristics were correlated with all TSH and FT4 levels within the normal range and compared between two groups (TSH cut-off < and ≥2.5 mIU/L).

RESULTS

Tobacco use was associated with higher serum TSH levels (OR: 1.38; CI 95%: 1.08-1.74); P = 0.009. FT4 levels were inversely correlated with age and BMI (rho = -0.096 and -0.089; P < 0.001 and 0.001 respectively) and positively correlated with ferritin levels (rho = 0.097; P < 0.001). Postpartum haemorrhage (>500 mL) was inversely associated with serum FT4 levels (OR: 0.35; CI 95%: 0.13-0.96); P = 0.040. Also 10% of women free of thyroid disease had serum TSH levels ≥2.5 mIU/L.

CONCLUSIONS

Variation in thyroid function during the first trimester within the normal (non-pregnant) range in women free of thyroid disease was not associated with altered pregnancy outcomes. These results add evidence to the recommendation against LT4 treatment in pregnant women with high normal TSH levels and without TPO antibodies.