The PHIME project (Public health impact of long-term, low-level, mixed element exposure in susceptible population strata) evaluated the association between low-level prenatal mercury (Hg) exposure through maternal fish consumption and child neurodevelopment in a coastal area of the north east of Italy. As part of this study the investigators also estimated how the child’s neurocognitive abilities at 18 months of age (assessed by the Bayley Scales of Infant and Toddler Development Third Edition, BSID III) were associated with maternal IQ (assessed by Raven’s Standard Progressive Matrices), the home environment (assessed using the AIRE instrument), and the family’s socio-economic status (assessed using the SES Index). Data from 502 mother-child pairs were analyzed. Home environment, socioeconomic status and maternal intelligence were connected with each other in affecting the different domains of early child development. Home environment had the greatest influence on neurodevelopment at 18 months. Promotion of autonomy within the home environment played a crucial role, in this age group, in all observed domains (cognitive, language and motor).