An adjective appearing as G. {gaib >>} gaiw “pregnant” in the Gnomish Lexicon of the 1910s (GL/37), derived from primitive ᴱ✶gīwă with the Gnomish sound change of ī > ai (GG/14).
Neo-Sindarin: I would adapt this word as ᴺS. gaew “pregnant” representing the Sindarin sound change of ai > ae, derived from the Neo-Root ᴺ√GIW having to do with pregnancy. In Tolkien’s later conception of the languages, its primitive form would need to be ✱gaiwa, the result of a-fortification of the root: compare [N.] maew “gull” derived from the root ᴹ√MIW (Ety/MIW).
A neologism for “pregnant” appearing in ABNW (ABNW) from the early 2000’s, a combination of [ᴹQ.] lapse “baby” and [ᴹQ.] lunga “heavy”, so literally “✱baby-heavy”. In his NQNT (NQNT), Helge Fauskanger instead used ᴺQ. lapsarwa with final element [ᴹQ.] arwa “having, possessing” (so = “✱baby-having”), but I prefer lapselunga as more evocative.