Impact of Maternal and Neonatal Factors on Thyroid-Stimulating Hormone Concentrations in Newborns in Eastern Morocco

Congenital hypothyroidism (CH) is a major preventable cause of intellectual disability. Neonatal screening based on thyroid-stimulating hormone (TSH) levels enables early detection and intervention. While maternal health conditions and exposures during pregnancy are known to affect newborn TSH levels, the newborn's own characteristics may also influence these results.

A cross-sectional study was conducted on 1,119 mothers and their newborns in the region of Eastern Morocco. A survey was conducted to collect sociodemographic data, anthropometric data, and medical history. For the newborns, in addition to a clinical examination, heel prick samples were collected on blotting papers, and an immunofluorimetric method was used to quantify TSH.

The analysis of maternal factors revealed a highly significant association between maternal thyroid dysfunction and TSH concentrations in newborns (p < 0.001, OR = 11.365). Drug use during pregnancy was also strongly associated (p = 0.014, OR = 3.230), especially anti-thyroid treatment (p < 0.001, OR = 18.218). Conversely, other factors, such as anthropometric indicators and pregnancy-related conditions (hypertension, diabetes), showed no statistically significant association. As for neonatal factors, high TSH levels were significantly more frequent in preterm infants (p = 0.006, OR = 4.09), whereas no significant associations were found with other factors (sex, birth weight, or length). Hypotonia and feeding difficulties were more prevalent in newborns with elevated TSH but did not reach statistical significance.

Both maternal and neonatal factors may influence neonatal TSH values, in particular, prematurity. The results also show the direct impact of maternal thyroid disorders on the newborn's thyroid function. This explains the importance of contextual interpretation of TSH results in neonatal screening, but also the importance of screening and treating maternal thyroid dysfunction during pregnancy.