Geographical distribution
Our conclusion showed that the geographical distribution of study sites with pregnant women is significantly uneven, which is common in China. The study sites where many drug trials in pregnant women were conducted are tertiary hospitals in developed cities. This geographical difference was due to the uneven distribution of higher level of clinical trial institutions, rather than the uneven distribution of patients35. According to guidelines issued by NMPA on May 11, the clinical trial agency certification system will be replaced by a new records management system. Before carrying out a clinical trial at an eligible medical institution, simply register on the NMPA-authorized website. The purpose is to promote the formation of a highly positive medical innovation environment36. At the same time, the pharmaceutical companies, ethics committees and CROs will take more responsibility in the clinical trials.