The package inserts revision regarding prescription drugs is an ongoing process. In this study, we examined the status of this revision and how the content of the information provided has been updated with the new instructions, including the rationale for contraindications for pregnant and breast-feeding women. A total of 407 prescription drugs for pregnant and breast-feeding women were contraindicated, accounting for approximately 15% of the 2,627 nonproprietary names. The number of contraindicated drugs for pregnant, breast-feeding, and both pregnant and breast-feeding women were 406, 44, and 43, respectively. The majority of the contraindications were based on nonclinical data, such as teratogenicity and fetotoxicity data in reproductive toxicity studies involving pregnant animals and pharmacokinetic information in breast-feeding animals. The overall revision rate for the new instructions was 16.2% after three years of revision work for each drug. The alert wording has been revised to provide more clarity and consistency, with three categories of statements: “should not be administered/avoid breastfeeding,” “advisable not to administer/breastfeed,” and “should be administered/breastfeed in consideration of the therapeutic benefit (benefit-risk consideration).” The statement indicating that the drug should not be administered to pregnant women remained in the revised instructions. Conversely, the revision of the description for breast-feeding women from “should be discontinued/avoided” to “benefit-risk consideration” may have improved the usefulness of the product, allowing healthcare professionals to make more informed decisions after considering the transfer of the drug into milk, its pharmacological effects, and other factors.