Do Thyroid Diseases during Pregnancy and Lactation Affect the Nutritional Composition of Human Milk?

Abstract

Objective To identify whether the effects of thyroid disease during pregnancy and lactation affect the nutritional composition of human milk. Methods Systematic review of the scientific literature using the Medical Literature Analysis and Retrieval System Online/MedLine databases to evaluate the association of thyroid diseases during pregnancy and lactation with the nutritional composition of human milk. There was no delimitation by period or by language, and the searches were completed in March 2019. The following descriptors were applied: human milk AND thyroid AND composition, using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) protocol for data search, selection, and extraction. The flowchart proposed for bibliographic search resulted in 12 articles and, of these, four were selected. Results The articles elected for this review were published between 1976 and 2018. Two studies found significant differences in the nutritional composition of mothers' milk with hypothyroidism or overweight compared with the milk of those without hypothyroidism. Studies have shown that the presence of the disease led to changes in the nutritional composition of human milk, especially a higher concentration of human milk fat. Conclusion It is extremely important that these women have continuous nutritional follow-up to minimize the impact of these morbidities on the nutritional composition of human milk.

Uncontrolled Thyroid during Pregnancy Alters the Circulative and Exerted Metabolome

“…Other studies comparing the human milk of patients with thyroid disorder to that of healthy subjects have reported changes in the protein, fat and lactose compositions of the human milk, evident only after the first week postpartum [30]. Such alterations in the composition of human milk can be explained since thyroid hormones are implicated in the pathways that mediate the tissue metabolism of carbohydrates, lipids and proteins [52].…”

“…Another biofluid gaining increasing attention in studies on the effects of hypothyroidism on lactation is colostrum, which is produced until the 7th day postpartum and constitutes the optimal food for all newborns. It contains bioactive compounds that establish the immune protection of infants, thus providing multiple advantages for infants' mental and physical development [29,30]. A number of studies have documented that hypothyroidism has an impact on both the quantity of human milk and the milk's protein composition [31,32].…”