Background: Hypothyroidism has been related to low-weight births, abortion and prematurity,
which have been associated with changes in the content of glycogen and vascularization of the
placenta. Since hypothyroidism can cause dyslipidemia, it may affect the lipid content in the uterus
affecting the development of fetuses.
Objective: To investigate the effect of hypothyroidism on the lipid levels in serum and uterus during
pregnancy and their possible association with the size of fetuses.
Method: Adult female rabbits were grouped in control (n = 6) and hypothyroid (n = 6; treated with
methimazole for 29 days before and 19 days after copulation). Food intake and body weight were daily
registered. At gestational day 19 (GD19), dams were sacrificed under an overdose of anesthesia. Morphometric
measures of fetuses were taken. Total cholesterol (TC), triglyceride (TAG), and glucose
concentrations were quantified in blood, uterus and ovaries of dams. The expression of uterine 3β-
hydroxysteroid dehydrogenase (3β-HSD) was quantified by Western blot.
Results: Hypothyroidism reduced food intake and body weight of dams, as well as promoted low abdominal
diameters of fetuses. It did not induce dyslipidemia and hyperglycemia at GD19 and did not
modify the content of lipids in the ovary. However, it reduced the content of TAG and TC in the
uterus, which was associated with uterine hyperplasia and an increased expression of 3β-HSD in the
Conclusion: Hypothyroidism alters the lipid content in the uterus that might subsequently affect the
energy production and lipid signaling important to fetal development.