I had a look for you in the OED and here is the most interesting part (highlight is mine):
[a. OF. concev-eir, -oir, (stressed
stem conˈceiv-):—L. concipĕre, f. con-
altogether + capĕre to take. The F.
form of the word is assimilated to
verbs in -ēre, while other Romanic
langs. have -ĕre, -īre: cf. Pr.
concebre, Sp. concebir, It. concépere
and -cepére. Nearly all the senses
found in Fr. and Eng. were already
developed in L., where the primary
notion was app. ‘to take effectively,
take to oneself, take in and hold’.
The development is thus partly
parallel to that of catch (esp. in
branches VII, VIII), which word may be
substituted for conceive in some
Having understood that the various senses already existed in the Latin word concipĕre, I turned to the extensive Perseus corpus of Latin works, which I warmly recommend.
I did not read all of the 5 pages of results. I just focused on classical Latin.
- Cicero, Livy use it in a great
variety of ways (conceive feelings or ideas
"have a take on" events).
- Pliny and Lucretius use extensively the term in its biological sense.
- Later scholar works also use it in a medical sense of "showing symptoms of" (fever).
I also looked up concipio in the Oxford Latin Dictionary (1968) and there are no less than 13 different meanings for this verb. Only 2 of them in the sense of to "engender".
So there's no clear cut answer even in classical Latin, I'm afraid.
The only indication comes from the OED clause "where the primary notion was app. ‘to take effectively, take to oneself, take in and hold".