One of the commonly used strategies for mothers to combine work with family life is to reduce their working hours, and move to a part-time job (Visser, 2002). Although part-time work could increase perceived work-life balance of workers, it also entails career sacrifices that (can) have consequences for the rest of the career (Yerkes, 2009). Another strategy that is frequently adopted by companies is to allow workers to combine work with family demands by working flexibly (Eurofound, 2015) – e.g., flexi-time that allow flexibility in starting and ending time of one’s work, and tele-working that allows workers to work from home. Studies have shown that flexible working can allow a better work-life balance (Allen et al., 2013) and can potentially increase parent’s time spent with children (Craig and Powell, 2012). However, it is still unclear whether flexible working patterns can be used as substitutes for part-time work, i.e., whether mothers are likely to retain their working hours if they are allowed to work flexibly. If this would be the case, allowing mothers to work flexibly can help reduce gender inequalities in labour market outcomes after childbirth. We examine the UK case, where the right to request flexible working has been expanded quickly over the past decade and where flexible working is being promoted as a major way to address work-life balance issues. The data used is Understanding Society (2009-2013), a large Household Panel survey with data on various types of flexible work arrangements including flexitime, working a compressed week, and regularly working from home. The analysis proposed is a competing risk event history model where we examine the effect of having a first child on the likelihood of remaining working full-time (versus part-time or not working) and compare the risks between mothers with and without various flexible working arrangements.