A stay-at-home dad (alternatively, stay at home father, house dad, SAHD, househusband, or house-spouse) is a father who is the main caregiver of the children and is the homemaker of the household. As families have evolved, the practice of being a stay-at-home dad has become more common, and socially more acceptable. Pre-industrialisation, the family worked together as a unit and was self-sufficient. Beginning with the Industrial Revolution, large-scale production replaced home manufacturing; this shift, coupled with prevailing norms governing sex or gender roles, dictated that the father become the breadwinner and the mother the caregiver. When affection-based marriages emerged in the 1830s, parents began devoting more attention to children and family relationships became more open. Beginning during World War II, many women entered the workforce out of necessity; women resumed the caregiver position after the war, but their new-found sense of independence changed the traditional family structure together with cultural shifts leading to the feminist movement and advances in birth control. Some women opted to return to the care giver role. Others chose to pursue careers. When women chose to work outside of the home, alternative childcare became a necessity. If childcare options were too costly, unavailable, or undesirable, the stay-at-home dad became a viable option.