MCCC allows the player to turn off alien abductions completely. I haven't checked my settings for a very long time so I can't say with any certainty one can allow abductions but stop the pregnancies from happening. And I agree we don't need the teams to play around with these features if there are mods that allow us to control abductions and pregnancies without totally nerfing the abduction feature for the players that use it. I believe one can also adjust the frequency of abductions with MCCC. I haven't played around with my MCCC settings for a long time but you can read the documentation for each MCCC module that has more info.
