Postpartum thyroid function following LT4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high-normal TSH: a retrospective study

Abstract Background Levothyroxine (LT4) therapy is commonly initiated in women undergoing infertility treatment who have high-normal thyroid-stimulating hormone (TSH) levels (HN) or subclinical hypothyroidism (SCH). However, there are no clear postpartum management guidelines for these patients. Met...

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Main Authors: Yuka Tsukamoto, Yoh Hidaka, Yoshiko Fukuda, Yuko Wada, Kazuyo Okamoto, Yasuyuki Okamoto
Format: Article
Language:English
Published: BMC 2025-07-01
Series:BMC Endocrine Disorders
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Online Access:https://doi.org/10.1186/s12902-025-02002-2
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author Yuka Tsukamoto
Yoh Hidaka
Yoshiko Fukuda
Yuko Wada
Kazuyo Okamoto
Yasuyuki Okamoto
author_facet Yuka Tsukamoto
Yoh Hidaka
Yoshiko Fukuda
Yuko Wada
Kazuyo Okamoto
Yasuyuki Okamoto
author_sort Yuka Tsukamoto
collection DOAJ
description Abstract Background Levothyroxine (LT4) therapy is commonly initiated in women undergoing infertility treatment who have high-normal thyroid-stimulating hormone (TSH) levels (HN) or subclinical hypothyroidism (SCH). However, there are no clear postpartum management guidelines for these patients. Methods We retrospectively analyzed 155 women (56 with HN, 99 with SCH) who initiated LT4 therapy during infertility treatment, discontinued it immediately after delivery, and underwent TSH measurement within 6 months postpartum. We evaluated postpartum TSH levels and their association with pre-treatment TSH, LT4 dose at delivery, thyroid volume, body weight, and thyroid autoantibodies. Receiver operating characteristic (ROC) curve analysis was performed to predict postpartum SCH. Results Postpartum TSH levels were significantly lower than pre-treatment levels (median 2.57 vs. 4.30 mIU/L, p < 0.001). TSH remained within the reference range in 78% of participants, while 15.7% had SCH and 6.3% had thyrotoxicosis. Higher pre-treatment TSH and higher LT4 dose at delivery were significantly associated with postpartum SCH (p < 0.001 for both). ROC analysis identified cutoff values of 4.82 mIU/L for pre-treatment TSH (area under the curve [AUC] = 0.785) and 71.4 µg/day for LT4 dose (AUC = 0.753). Postpartum thyrotoxicosis occurred in 6.3% of participants, all of whom were antibody-positive. Only two women required LT4 resumption after one year postpartum due to TSH ≥ 10 mIU/L. Conclusions For women with HN or SCH who initiated LT4 therapy during infertility treatment, immediate discontinuation of LT4 after delivery appears generally safe. Nevertheless, postpartum thyroid function should be closely monitored, particularly in antibody-positive patients or those with elevated pre-treatment TSH.
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spelling doaj-art-e70193b1fd7a4dbd86e6f8fc963f39fb2025-08-20T03:43:16ZengBMCBMC Endocrine Disorders1472-68232025-07-012511710.1186/s12902-025-02002-2Postpartum thyroid function following LT4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high-normal TSH: a retrospective studyYuka Tsukamoto0Yoh Hidaka1Yoshiko Fukuda2Yuko Wada3Kazuyo Okamoto4Yasuyuki Okamoto5Okamoto Thyroid ClinicOkamoto Thyroid ClinicOkamoto Thyroid ClinicOkamoto Thyroid ClinicOkamoto Thyroid ClinicOkamoto Thyroid ClinicAbstract Background Levothyroxine (LT4) therapy is commonly initiated in women undergoing infertility treatment who have high-normal thyroid-stimulating hormone (TSH) levels (HN) or subclinical hypothyroidism (SCH). However, there are no clear postpartum management guidelines for these patients. Methods We retrospectively analyzed 155 women (56 with HN, 99 with SCH) who initiated LT4 therapy during infertility treatment, discontinued it immediately after delivery, and underwent TSH measurement within 6 months postpartum. We evaluated postpartum TSH levels and their association with pre-treatment TSH, LT4 dose at delivery, thyroid volume, body weight, and thyroid autoantibodies. Receiver operating characteristic (ROC) curve analysis was performed to predict postpartum SCH. Results Postpartum TSH levels were significantly lower than pre-treatment levels (median 2.57 vs. 4.30 mIU/L, p < 0.001). TSH remained within the reference range in 78% of participants, while 15.7% had SCH and 6.3% had thyrotoxicosis. Higher pre-treatment TSH and higher LT4 dose at delivery were significantly associated with postpartum SCH (p < 0.001 for both). ROC analysis identified cutoff values of 4.82 mIU/L for pre-treatment TSH (area under the curve [AUC] = 0.785) and 71.4 µg/day for LT4 dose (AUC = 0.753). Postpartum thyrotoxicosis occurred in 6.3% of participants, all of whom were antibody-positive. Only two women required LT4 resumption after one year postpartum due to TSH ≥ 10 mIU/L. Conclusions For women with HN or SCH who initiated LT4 therapy during infertility treatment, immediate discontinuation of LT4 after delivery appears generally safe. Nevertheless, postpartum thyroid function should be closely monitored, particularly in antibody-positive patients or those with elevated pre-treatment TSH.https://doi.org/10.1186/s12902-025-02002-2Infertility treatmentSubclinical hypothyroidismHigh-normal TSHLevothyroxine therapyPostpartum thyroid function
spellingShingle Yuka Tsukamoto
Yoh Hidaka
Yoshiko Fukuda
Yuko Wada
Kazuyo Okamoto
Yasuyuki Okamoto
Postpartum thyroid function following LT4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high-normal TSH: a retrospective study
BMC Endocrine Disorders
Infertility treatment
Subclinical hypothyroidism
High-normal TSH
Levothyroxine therapy
Postpartum thyroid function
title Postpartum thyroid function following LT4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high-normal TSH: a retrospective study
title_full Postpartum thyroid function following LT4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high-normal TSH: a retrospective study
title_fullStr Postpartum thyroid function following LT4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high-normal TSH: a retrospective study
title_full_unstemmed Postpartum thyroid function following LT4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high-normal TSH: a retrospective study
title_short Postpartum thyroid function following LT4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high-normal TSH: a retrospective study
title_sort postpartum thyroid function following lt4 treatment from infertility treatment to delivery in women with subclinical hypothyroidism or high normal tsh a retrospective study
topic Infertility treatment
Subclinical hypothyroidism
High-normal TSH
Levothyroxine therapy
Postpartum thyroid function
url https://doi.org/10.1186/s12902-025-02002-2
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