Objective: Hazardous working conditions increase the risk of adverse pregnancy outcomes. In this study, we examine adherence to legislation and guidelines aimed at improving working conditions in pregnancy. Methods: Between 2014 and 2016, we recruited a prospective cohort of low-risk nulliparous pregnant women in paid employment or self-employed in 16 community midwifery practices in The Netherlands. Participants completed two questionnaires concerning demographics, education, general health and working conditions between 10–16 and 20–24 weeks of pregnancy. We calculated the proportion of participants with work-related risk factors not in accordance with legislation and/or guidelines. Results: Of 269 participants included, 214 (80%) completed both questionnaires. At 10–16 weeks 110 (41%) participants and at 20–24 weeks 129 (63%) participants continued to work under circumstances that did not meet recommendations. Employers provided mandated information on work adjustment to 37 (15%) participants and 96 (38%) participants received no information about the potential hazards while working with biological and chemical hazards. Participants with lower educational attainment (aOR 2.2 95%CI 1.3–3.9), or employment in healthcare (aOR 4.5, 95%CI 2.2–9.0), education/childcare and social service (aOR 2.6, 95%CI 1.1–6.0 2), catering (aOR 3.6, 95%CI 1.1–12) and industry, construction and cleaning (aOR 3.3, 95%CI 1.1–10.3) more often continued work which did not meet recommendations. Conclusion: There is poor adherence to national legislation and guidelines for safe working in pregnancy in The Netherlands: 50% of the pregnant women worked under hazardous conditions. Given the impact on adverse pregnancy outcomes as well as on the public purse, action to improve compliance must be taken by all stakeholders.