Gnomish
gwectha-
verb. to impregnate, generate
gaibra-
verb. to impregnate
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
A verb appearing as G. gaibra- “to impregnate” in the Gnomish Lexicon of the 1910s, a verb form of G. gaib “pregnant” (GL/37), likely related to primitive ᴱ√giu̯i (GL/39). Elsewhere in this document there was another verb G. gwectha- based on G. gweg “man”, which meant “impregnate” when used with the allative and “generate” when used with the accusative.
Neo-Sindarin: I posit the existence of Neo-Root ᴺ√GIW to serve as the basis for pregnancy words, so I would adapt the above verbs as causative ᴺS. gýda- “to impregnate, make pregnant” < ✱giu̯-tā-, with iu > ȳ as usual in Sindarin.