Motherism is a growing prejudice against stay-at-home mums which suggests that full-time mothers are unintelligent, unattractive and just plain lazy because they're not in formal employment. This entrenched lack of respect can mean that relative to their professional counterparts, full-time mums are held in lower esteem and regarded as less interesting individuals who've taken a downwards step both socially and intellectually because they've elected to stay at home.
The use of motherism as a description of prejudice against stay-at-home mothers is attributed to Dr Aric Sigman, a biologist and psychologist renowned for his commentary on parenting issues and the merits of traditional values. Following the derivational pattern of racism, sexism, etc, there's also some evidence for use of motherist as both an adjective to describe such attitudes and a countable noun for people who perpetuate them. (Source: macmillandictionary.com)