Many components of abortion care in early pregnancy can safely be provided on an outpatient basis by mid-level providers or by pregnant people themselves. Yet, some states impose non-evidence-based provider restrictions, understood as legal or regulatory restrictions on who may provide or manage all or some aspects of abortion care. These restrictions are inconsistent with the World Health Organization’s support for the optimization of the roles of various health workers, and do not usually reflect evidence-based determinations of who can provide abortion. As a matter of international human rights law, states should ensure that the regulation of abortion is evidence-based and proportionate, and disproportionate impacts must be remedied. Furthermore, states are obliged take steps to ensure women do not have to undergo unsafe abortion, to reduce maternal morbidity and mortality, and to effectively protect women and girls from the physical and mental risks associated with unsafe abortion. States must revise their laws to ensure this. Where laws restrict those with the training and competence to provide from participating in abortion care, they are prima facie arbitrary and disproportionate and thus in need of reform. This review, developed by experts in reproductive health, law, policy, and human rights, examined the impact of provider restrictions on people seeking abortion, and medical professionals. The evidence from this review suggests that provider restrictions have negative implications for access to quality abortion, contributing inter alia to delays and recourse to unsafe abortion. A human rights-based approach to abortion regulation would require the removal of overly restrictive provider restrictions. The review provides evidence that speaks to possible routes for regulatory reform by expanding the health workforce involved in abortion-related care, as well as expanding health workers' roles, both of which could improve timely access to first trimester surgical and medical abortion, reduce costs, save time, and reduce the need for travel.