Neurotrophic Growth Factors in Breast Milk

The goal of this observational study is to demonstrate the presence of neurotrophic factors in the breast milk of mothers with 18-month-old children and the persistence of these factors in breast milk after the age of 2 years. The main questions it aims to answer are: * Does the breast milk of mothers with 18-month-old babies contain Brain-Derived Neurotrophic Factor (BDNF), S100B protein and glial cell line-derived neurotrophic factor (GDNF)? * Does the breast milk continue to contain BDNF, s100B protein and GDNF and-after 24 months? Participants will be asked to give breastmilk at 3 separate times. Breast milk samples will be collected from mothers at 18th-month, 24th-month and ≥25 months of their babies. A total of 75 breast milk samples obtained from 25 mothers with their consent will be analyzed.