Postpartum Follow-Up of Women Who Developed Subclinical Hypothyroidism during Pregnancy

Abstract

There is inconsistency in the literature regarding the management of women diagnosed with subclinical hypothyroidism (SCH) during pregnancy in the postpartum period. The purpose of our study was to assess the need for continuation of levothyroxine (LT4) treatment after delivery. We conducted a retrospective cohort study of 114 women with new-onset SCH during pregnancy and at 1-year follow-up postpartum. Criteria for continuation of LT4 after delivery were breastfeeding, thyrotropin (TSH) levels at diagnosis >5 mIU/L, positive antithyroid antibodies and LT4 dose before delivery >50 μg/day. On treatment initiation, mean TSH ± SD was 5.24 ± 2.55 mIU/L. One year after delivery, most patients (86/114) were still on LT4. This was related to TSH levels at the initiation of treatment in gestation (p = 0.004) and inversely related to primiparity (p = 0.019). In the group of patients who stopped LT4 postpartum, treatment was reinstated in 11 out of 39 (28.2%) due to SCH relapse (mean TSH ± SD = 9.09 ± 5.81 mIU/L). Most women in our study continued treatment after delivery, and a considerable number of women who had discontinued LT4 restarted treatment postpartum. These results stress the need to reassess thyroid function at 6 to 12 months postpartum.

Long-term hypothyroidism in patients started on levothyroxine during pregnancy

“…This dose, larger more than the 50 µg cut-off suggested by ATA guidelines (3), might be explained by the inclusion of OH patients with higher peri-conception TSH levels and greater substitution need during pregnancy. In our long-term hypothyroid patients, like in the study by Li et al (10), the LT4 treatment was initiated at an earlier gestational age, demonstrating the lack of adaptation of these patients to the metabolic stress of the pregnancy.…”

“…We show in our study that the TSH level at treatment initiation and the maximal LT4 dose during pregnancy are predictive of persistent hypothyroidism. Previous studies have found associations between long-term hypothyroidism and TSH >5 mU/l at diagnosis (6,7,10), LT4 dose at the end of pregnancy (7), TPOAb (6)(7)(8) or TgAb (8) positivity at diagnosis and at 6 weeks post-partum follow-up (8), gestational age at treatment initiation (8), multiparity (10) or maternal age (7). TSH was significantly higher at LT4 initiation in patients who were long-term hypothyroid in our study and a TSH level >3.8 mU/l was predictive of this evolution.…”

“…These patients account for almost one third of long-term hypothyroid patients and could lead to an overestimation of the persistence of hypothyroidism. In the study by Linardi et al, the prevalence of persistent hypothyroidism goes down from 75.5% to 28% when only the patients who discontinued the treatment are analysed (10).…”

“…However, a post-partum followup might not be necessary in some patients, for instance in those with isolated hypothyroxinemia, giving the low prevalence of persistent hypothyroidism in this group (8,12). A normal thyroid function at 6 weeks post-partum does not exclude the risk of long-term hypothyroidism, that can develop in 28% of patients followed for a median of 11 (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)) months (8), especially when thyroid antibodies are positive.…”