The Messenger of Allah ﷺ said, "There are five categories of people who, if they die in any of these states, are martyrs. The one killed in the path of Allah is a martyr, the one who drowns in the path of Allah is a martyr, the one who dies of a stomach illness in the path of Allah is a martyr, the one who dies of plague in the path of Allah is a martyr, and the woman who dies in childbirth in the path of Allah is a martyr."
أخبرنا يونس بن عبد الأعلى قال حدثنا ابن وهب قال حدثني عبد الرحمن بن شريح عن عبد الله بن ثعلبة الحضرمي أنه سمع ابن حجيرة يخبر
أن رسول الله ﷺ قال خمس من قبض في شيء منهن فهو شهيد المقتول في سبيل الله شهيد والغرق في سبيل الله شهيد والمبطون في سبيل الله شهيد والمطعون في سبيل الله شهيد والنفساء في سبيل الله شهيد
Reference, [sahih]. It is in Kubra, no. 4371, and it has a corroborating narration mentioned earlier, no. 2056, and Munziri, 2/334, indicated that it is hasan. Abdullah bin Thalaba was not deemed reliable by anyone other than Ibn Hibban.