It is narrated from Hazrat Safwan bin Umayyah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: Death due to plague, abdominal disease, drowning, or dying in the state of postnatal bleeding is also martyrdom.
Hadith Referenceمسند احمد / من مسند القبائل / 27641
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد ضعيف لجهالة عامر بن مالك