© 2018 The Author(s). Background: In Japan, although the number of females who continue to work after marriage has recently increased, the proportion of those working while parenting their infants is still not clearly increasing, indicating that it is still difficult for them to continue working after delivery. The present study aimed to clarify factors influencing females' continuation of work, using data obtained by continuously following up the same subjects and focusing on occupation changes, family environments, and the type of employment after pregnancy or delivery. Methods: Based on the results of the questionnaire survey, which was conducted involving 164 participants at 4 universities, as part of the Japan Environment and Children's Pilot Study (JECS Pilot Study) led by the Ministry of Environment and the National Institute for Environmental Studies, the occupational status was compared between the detection of pregnancy (weeks 0 to 7) and 1year after delivery. Results: <Non-regular employees> compared with <regular employees> changed their occupations significantly more frequently (OR=5.07, 95% CI=2.57-10.01, P<0.001). Furthermore, on examining <non-regular employees> in detail, occupation changes were particularly marked among <part-time and short-term contract employees> (OR=12.48, 95% CI=4.43-35.15, P<0.001). This tendency was especially shown among <<those engaged in specialized or technical work>>(OR=10.36, 95% CI=1.59-67.38, P=0.014) and<<those engaged in clerical work or management>>(OR=15.15, 95% CI=2.55-90.17, P=0.003). Conclusions: Analysis revealed that the type of employment, rather than the category of occupation, was associated with the continuation of work after pregnancy or delivery more closely, as <non-regular employees> compared with <regular employees> continued to work less frequently. Furthermore, on comparison of the category of occupation among <regular employees>, <<those engaged in specialized or technical work>>and<<those engaged in clerical work or management>>were shown to be more likely to continue to be engaged in the same occupation after pregnancy or delivery. These differences may be related to availability of the child-care leave program and other support resources, therefore, it may be important to establish social systems that enable all females, to use these support resources if they wish, and actively work, while delivering and parenting their children.