In many countries, temporary work is negatively associated with fertility. Yet, the mechanisms underlying this relationship remain poorly understood. This study investigates a range of mediating pathways (subjective and objective financial situation, short tenure, and employment uncertainty) through which temporary work influences first births in two contrasting contexts: Australia and Germany. Event history and path models are estimated using 19 years of data from both the Household, Income and Labour Dynamics in Australia (HILDA) Survey (n=28,493) and the German Socio-Economic Panel Study (GSOEP) (n=31,480). Results show that casual work among women and men in Australia, and fixed- term contracts among women in Germany, are associated with a lower likelihood of first birth than permanent employment. Lower wages explained a significant proportion of these differentials for both genders. The higher likelihood of being new in a job (in Germany) and higher perceived job insecurity (in Australia) were also relevant mediators, but only among women. These gendered outcomes suggest that women, in their role as primary carers, place more value on obtaining secure and stable employment prior to first birth. For men, in their role as primary earners, securing higher-paying jobs matters more for fertility than a stable job.