Thyroid alterations in the first trimester of pregnancy

Basis and objectives: Thyroid alterations are frequent during pregnancy and can be harmful to the development of the newborn. The objective of this paper is to assess the prevalence of thyroid disorder (functional and structural) in a group of pregnant women during the first trimester.

Patients and methods: Descriptive observational survey, carried out within a health area in Toledo. The group of participants was composed of pregnant women from this area and a control group of non-pregnant women of similar age. TSH, free T4 and TPO levels were measured in pregnant women. In order to assess their thyroid volume, echoestructure and nodules, all women underwent a thyroid ecography.

Results: 189 pregnant women and a control group of 169 non-pregnant women participated. The prevalence of hypothyroidism in the pregnants group was 9.5% [IC95% 6.0–14.7]. The thyroid volume was larger in the group of pregnants (12.2±5.6 mL) than in the control group (10.7±4.0 mL) [p=0.005]. 14 out of 18 hypothyroid pregnant women (77.8%) showed thyroid echoestructure alterations versus 9 (5.3%) in the non-hypothyroid group [p=0.000].

Thyroid nodules were found in 38.5% of the women from the control group and 33.2% of the pregnant women [p=0.290].

Conclusions: The prevalence of hypothyroidism is high, similar to what other Spanish papers have found. Testing thyroid hormones and TPO during the first pregnancy control should be considered. The prevalence of nodules is similar in both groups: control and pregnant women during the first trimester. Thyroid echoestructure alterations are significantly more frequent in pregnant women with hypothyroidism. The prevalence of nodules is similar both in pregnants in the first trimester and non-pregnants.