Talk to your Slaves/Intimacy can make most minor slaves (who are marked by a f) and Peorth (if she is in love with you) pregnant. Shampoo can conceive via the Dickgirl Mother ending. If you edit configuration.xml in your Slavemaker 3 folder & change <DefaultFertility>0</DefaultFertility> to a positive number, that will be the percentage change of conception per act for any non-male slave that does not have fertility set (and some have it set to 0 & will never get pregnant). Intimacy may now impregnate any slave that does not have 0 fertility & impregnation can now also happen when the slave is used in a sex act where a male or (other) dickgirl is involved. Note that a female slavemaker can impregnate during Intimacy with the Iceni Feeldo.
A female/dickgirl slave maker may also become pregnant. Pregnancy will not occur if the female/dickgirl (slave maker or slave) is using contraceptives. The exception to this is Arak, who will make the slave maker pregnant even if contraceptives are used.
To get a minor slaves pregnant, its good to look on her Lust-bar sometimes. If the bar is colored as it is while using Nymph´s Tiara (purchased from the traveling merchant) your slave is fertile. (For those wondering why your slaves don´t get pregnant)
In order for pregnancy to occur, the slave maker must have Cora, to announce them.
List of fertile Slaves known:
Minor-slaves: ( sometimes even without lust-bar changed, but most times just at the beginning ) Cora, Maran, Laan, Lian & Dian, Latala, Sana, Lucina, Henrietta, Garnet, VilettaNu, Nephenee, Passel, Hanon, Rina, Mileena, Haro
Trained slaves: ( sometimes even without lust-bar changed, but most times just at the beginning ) Shampoo, Tifa, Minako, KallenStadtfeld, Charlotte, Erza, Holo (just while trained), Kirino, Saori, Mai
Event-slaves: Pfil (Achieved at the Farm), Adisa (Quest starts at the Beach while "going for a walk"), Arak (Quest starts randomly at the Secure Slave Pens of the Docks), Elena (Captured by walking in the Jungle at Susanoo´s Island. Go to there from the Docks.)
It should be mentioned, that these are only the proved ones. There can also be more, mostly the trained slaves. Rei and Morrigan are not to be "captured" by making them fall in love with you. Rei will be delivered even if she confessed her love, as Morrigan. In fact Morrigan is pretty hard to train, so be warned not to try her without saving before.