Maternal Hypothyroidism: Recognition and Management

Abstract

Women with compensated early thyroid failure, or those from areas of reduced iodine intake, may first be found to be hypothyroid during pregnancy. In women with previously diagnosed hypothyroidism already on thyroxine (T4) replacement therapy, pregnancy is often associated with an increased dose requirement. The mechanism producing this increased requirement is not known, but it is likely to be the result of a number of factors that may differ depending on the stage of pregnancy. An increased T4 dose requirement is typically seen by the first trimester, can continue to increase throughout pregnancy, and reverts to the prepregnancy dose requirement after delivery. The magnitude of the increased T4 requirement is related to the etiology of hypothyroidism. Monitoring thyroid status and adjusting the T4 dose during pregnancy is a challenge due to changes in T4 metabolism throughout pregnancy.

Overt and subclinical hypothyroidism among Bangladeshi pregnant women and its effect on fetomaternal outcome

“…This is consistent with previously reported cases. 16 In this present study it was observed that 27.6% and 80.0% babies had low (≥2.5 kg) birth weight in subclinical hypothyroidism patients and overt hypothyroidism patients respectively. Low birth weight and low APGAR score at 1 st minute were significantly (p<0.05) higher in overt hypothyroidism patients, but others were not significant (p>0.05).…”

Maternal Thyroid Dysfunction and Neonatal Thyroid Problems

“…Maternal thyroid deficiency, even subclinical, has been reported to be associated with adverse pregnancy outcomes that may be improved by T4 replacement [4]. Fluctuations that occur in T4 metabolism during pregnancy make it difficult to maintain meticulous normal thyroid hormone values during gestation in hypothyroid mothers [21]. Pregnancy causes increased thyroid gland vascularity, increased renal iodide clearance, and iodide losses to the foetus [1].…”

Dysthyroïdies et grossesse

“…La posologie de lévothy-roxine sera adaptée, afin de maintenir la concentration de la TSH inférieure à 2,5 mU/L pendant le premier trimestre de la grossesse et inférieure à 3 mU/L au cours des deuxième et troisième trimestres de la gestation [3], afin d'optimiser le traitement substitutif et prévenir ainsi les conséquences d'une hypothyroïdie maternelle sur le développement cérébral foetal. D'autre part, les besoins en lévothyroxine augmentent chez près de 80 % des femmes qui ont une hypothyroïdie connue avant la grossesse [2,3,32]. L'augmentation de la posologie, variable selon les patientes, ne semble pas liée à une diminution de l'absorption intestinale de la lévothyroxine (une théra-peutique martiale fréquemment prescrite doit être prise au moins trois heures après la prise de lévothyroxine).…”