This thesis examines how women's work in the period after first birth affects the timing of their next birth using work history and birth history data from the 1993 Philippine Demographic and Health Survey. It thereby overcomes some of the kinds of data and methodological problems that commonly contribute to doubt regarding whether work has a causal effect on fertility outcomes. The relationship between work and birth spacing in these data can provide us some insight regarding the role compatibility of work and childbearing in a setting with a high total fertility rate, low rates of modern sector employment for women, and low modern contraception use. The results show that women's work delays the occurrence of second birth. However, quick return to paid work is related to a higher hazard of second birth, and doing paid work is found to have a non-proportional effect at around sixteen month postpartum.