The doctor made a ‘hmm’ sound, nodding. “Well, according to our blood tests… you are nine weeks pregnant.”
“Pregnant?” Lois whispered in shock, mentally searching for any dates with Clark that had gone further than a perfunctory kiss during the last three months. “How—how is that possible? I mean—I don’t remember, uh, sleeping with anyone…
This episode is such a good opportunity for what-if fics that it's surprising that there is not a ton of fics exploring the possibilities. I guess most of the Smallville's viewers were not used to reading and writing fanfic.

I wish they had talked about it in the series at some point, maybe before their "first" time, that technically would be Clark's first time with Lois but Lois's second time with him. Back to the topic... At least Clark knows what happened. If nobody knew, the memories of their time together in the future would have been lost and the situation would be worse.