Pregnancy in Patients with Mild Thyroid Abnormalities: Maternal and Neonatal Repercussions*

Abstract

A prospective study was undertaken during pregnancy in 120 euthyroid women presenting with mild thyroid abnormalities (TA): 11 with a past history of thyroid disorder, 44 with goiter, 20 with nodules, and 45 with thyroid autoantibodies. The aims of the study were to assess whether the pattern of thyroid alterations during gestation was different in women with TA compared to that in healthy control pregnant subjects and to evaluate possible obstetrical and neonatal repercussions. The overall prevalence of underlying subtle thyroid abnormalities in the cohort was 17%, probably as the result of the environmental moderately low iodine intake. Despite the intrinsic heterogeneity of the four groups of women with TA, the adaptation of the thyroid to the stress of pregnancy was different from that of the control subjects. Noteworthy were 1) the marked elevation of serum thyroglobulin in women with past history of thyroid disorder, goiter and thyroid nodules; 2) the increase in goiter size in a third of the goitrous women, associated with biochemical evidence of functional stimulation of the gland; 3) the indirect evidence of partial thyroidal autonomy in goitrous patients; and 4) the increase in the number and size of thyroid nodules during gestation. Taken together, the data indicated that pregnancy was associated with a greater thyroidal risk in patients with TA compared to healthy subjects. In relation to thyroid autoimmunity, most patients remained euthyroid during gestation, but in a few cases, TSH was elevated at delivery, suggesting diminished thyroidal reserve. Also, 40% of newborns from mothers with thyroid autoimmunity had elevated thyroid peroxidase antibody titers at birth, and there was a highly significant correlation between maternal and neonatal thyroid peroxidase antibody titers. Finally, thyroid autoimmunity was clearly associated with an increased risk of spontaneous abortion (13.3 vs. 3.3%; P less than 0.001). Thyroid function in newborns from mothers with TA was normal and not different from that in controls; similarly, obstetrical features were similar in patients with TA and control subjects. In conclusion, pregnancy is associated with a greater thyroidal risk in women with TA, thereby emphasizing a potential link between pregnancy and thyroid disorders. It is recommended that patients with known, even subtle, thyroid abnormalities be closely monitored during pregnancy, in particular those with a goiter, nodules, or thyroid autoimmunity, especially in areas with a moderately low iodine intake, where the prevalence of mild thyroid disturbances is high.

Low concordance between positive antibodies to thyroperoxidase and thyroid ultrasound autoimmune pattern in pregnant women

“…The relationship between thyroid dysfunction, thyroid autoimmunity and the risk of preterm delivery (PTD) and complications of pregnancy has been well described [5,6]. The rate of PTD varied from 4 to 26.8 % in TPOAb-positive women and 3-8.2 % in TPOAbnegative controls [22,23,24,25].…”

“…eral studies risk of fetal loss and preterm delivery [5,6]. However, whether the TPOAb positivity is in some pregnant women only a laboratory phenomenon or it is always accompanied by morphological changes in TUS remains unclear.…”

Clinical practice guidelines for the management of hypothyroidism

“…The studies differed in various aspects. Some had followed a cohort (235)(236)(237)248,250,252,253,(260)(261)(262)(263)(264)(265)(266)(267)(268)(269)(270)(271) (B,A,B,B,B,B,B,A,B-B) and others were "case-controlled" studies (251,254,(272)(273)(274)(275) (C,C,C,C,C).…”

To study the neonatal outcomes in pregnancies with hypothyroidism in a tertiary referral centre

“…Earlier studies have reported increased prevalence of congenital anomalies (10-20%), perinatal mortality (20%) and impaired mental and somatic development (50-60%) in new born of untreated hypothyroid mothers. 5,6 The prevalence of preterm babies (gestational age <37 weeks) in group A is found to be 2%. And the prevalence of preterm babies in group B is 6%.…”