Maternal Hypothyroidism and Neonatal Obesity

What is it about?

A normal transportation of thyroid hormones (THs) from pregnant women to their fetuses/neonates is required for the normal development, particularly the energy homeostasis, appetite, basal metabolic rate (BMR) and metabolic mechanisms. In addition, mild maternal thyroid insufficiency (isolated hypothyroxinaemia; reduction in the level of free thyroxine (FT4) and an increase in the free triiodothyronine (FT3) to FT4 ratios) with poor obstetric outcomes during gestation can cause several adverse metabolic defects such as insulin resistance, glycaemia, obesity, and lipid profile disorders (hyper-lipidaemia). Also, the association between the maternal hypothyroxinaemia and obesity was observed in iodine-deficient pregnant women. It was supposed that obesity-induced the activities of peripheral deiodinases (Ds) increasing the energy expenditure, the conversion of FT4 to FT3 and eventually the FT3 to FT4 ratio. Thus, any disruption in the levels of THs during the gestation may cause obesity and suppress the neonatal development. Women have to avoid the hypothyroxinemia and any excess in the body weight gain. Maintaining normoglycaemia during pregnancy may play an important role in a healthy life for the newborns. However, additional studies are essential to replicate these observations and to explore the harmful effects of maternofetal thyroid dysfunction (hypothyroidism or isolated hypothyroxinaemia) and obesity (adverse metabolic parameters) on long-term growth and neonatal development. Furthermore, the connection between the molecular and epidemiological studies is required. This argument is still ambiguous because of the difficulties of the direct observation of thyroid dysfunction on obesity.

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Why is it important?

It was supposed that obesity-induced the activities of peripheral deiodinases (Ds) increasing the energy expenditure, the conversion of FT4 to FT3 and eventually the FT3 to FT4 ratio. Thus, any disruption in the levels of THs during the gestation may cause obesity and suppress the neonatal development. Women have to avoid the hypothyroxinemia and any excess in the body weight gain. Maintaining normoglycaemia during pregnancy may play an important role in a healthy life for the newborns.

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