Abu Atiyyah said: I heard Sayyiduna Ibn Mas'ud (may Allah be pleased with him) say: The verse of the shorter (surah), "And for those who are pregnant, their term is until they deliver their burden" [Surah al-Talaq: 4], was revealed after this verse of Surah al-Baqarah: "And those of you who die and leave behind wives, they (the wives) shall wait concerning themselves" [Surah al-Baqarah: 234].
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9611