Wage Equity Act of 2019 This bill addresses pay discrimination in the workplace between men and women. Specifically, the bill allows an employer to base a wage differential determination on an employee's participation in a flexible work arrangement; protects employers who conduct a pay analysis audit to identify and correct pay discrimination from liability for damages relating to such discrimination; makes it an unlawful practice for an employer to rely on the wage history of a prospective employee for hiring and wage determination purposes unless the wage history is voluntarily provided by the prospective employee; makes it an unlawful practice for an employer to prohibit an employee from requesting wage information from another employee or from requesting information about wage differentials; authorizes the Department of Labor to establish a grant program for negotiation skills training for women and girls; and requires the Government Accountability Office to study and report on the causes and effects of pay disparities among men and women in the workplace and the impact on pay and opportunity for employees who leave the workforce for parental reasons.