birth (n.)

Old English bæð "an immersing of the body in water, mud, etc.," also "a quantity of water, etc., for bathing," from Proto-Germanic *badan (source also of Old Frisian beth, Old Saxon bath, Old Norse bað, Middle Dutch bat, German Bad), from PIE root *bhē- "to warm" + *-thuz, Germanic suffix indicating "act, process, condition" (as in birth, death). The etymological sense is of heating, not immersing.

The city in Somerset, England (Old English Baðun) was so called from its hot springs. Bath salts is attested from 1875 (Dr. Julius Braun, "On the Curative Effects of Baths and Waters"). Bath-house is from 1705; bath-towel is from 1958.

Old English beran "to carry, bring; bring forth, give birth to, produce; to endure without resistance; to support, hold up, sustain; to wear" (class IV strong verb; past tense bær, past participle boren), from Proto-Germanic *beranan (source also of Old Saxon beran, Old Frisian bera "bear, give birth," Middle Dutch beren "carry a child," Old High German beran, German gebären, Old Norse bera "carry, bring, bear, endure; give birth," Gothic bairan "to carry, bear, give birth to"), from PIE root *bher- (1) "carry a burden, bring," also "give birth" (though only English and German strongly retain this sense, and Russian has beremennaya "pregnant").

The Old English past tense bær became Middle English bare; the alternative bore began to appear c. 1400, but bare remained the literary form till after 1600. Past-participle distinction of borne for "carried" and born for "given birth" is from late 18c.

Many senses are from the notion of "move onward by pressure." To bear down "proceed forcefully toward" (especially in nautical use) is from 1716.  The verb is attested from c. 1300 as "possess as an attribute or characteristic." The meaning "sustain without sinking" is from 1520s; to bear (something) in mind is from 1530s; the meaning "tend, be directed" (in a certain way) is from c. 1600. To bear up is from 1650s as "be firm, have fortitude."