Gnomish
gaib
adjective. *pregnant
gaiw
adjective. pregnant
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
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).