Adam Clarke on Isaiah 26:18

We have - brought forth wind - The learned Professor Michaelis explains this image in the following manner: "Rariorem morbum describi, empneumatosin, aut ventosam molam, dictum; quo quae laborant diu et sibi et peritis medicis gravidae videntur,tandemque post omnes verae graviditatis molestias et labored ventum ex utero emittunt: quem morbum passim describunt medici. "Syntagma Comment., vol. ii., p. 165. The empneumatosis, or windy inflation of the womb, is a disorder to which females are liable. Some have had this in such wise, for a long time together, that they have appeared to themselves, and even to very skillful medical men, to be pregnant; and after having endured much pain, and even the throes of apparent childbearing, they have been eased and restored to health by the emission of a great quantity of wind from the uterus. This disorder is well known to medical men. "The Syriac translator seems to have understood it in this manner: Enixi sumus, ut illae quae ventos pariunt. "We have brought forth as they who bring forth wind."

In the earth "In the land" - בארץ bearets; so a MS., the Septuagint, Syriac, and Vulgate.