Conception was a moment in sexual reproduction in which a sperm fertilizes the ovum, thus beginning the development of a fetus.
The Scathos civilization prevented any woman from conceiving before the age of 40 at the penalty of death. (VOY: "Elogium")
In 2268, sympathetic to the plight of the planet Gideon, which was quickly becoming overpopulated, James T. Kirk asked Hodin to allow his people to learn about devices which safely prevented conception. (TOS: "The Mark of Gideon")
In the 2360s, the geneticists on Moab IV were able to screen out any cogenital health risks prior to conception. (TNG: "The Masterpiece Society")
Asil, the youngest child of Tuvok and T'Pel, was conceived during Tuvok's eleventh pon farr. (VOY: "Elogium", "Alice", "Unimatrix Zero, Part II")
In the 2370s, ovarian resequencing enzymes were a type of medical enzyme used to permit conception between two persons of different species. (DS9: "Tears of the Prophets")
In 2373, Human research scientist Elias Giger developed a theory that the cells in one's body did the "same dull monotonous routine" from the day a person was conceived, repeatedly metabolizing and dividing, until they became bored and simply gave up. (DS9: "In the Cards")
In 2375, Captain Benjamin Sisko forgot to renew his contraception injection which would have prevented his wife from becoming pregnant with their first child. (DS9: "The Dogs of War")
The prophecies surrounding the Klingon Kuvah'magh suggested the saviour of the Klingon people would be conceived during the holy month of nay'Poq. In 2377, the D7-class battle cruiser captained by Kohlar believed they had discovered the Kuvah'magh as Miral Paris, the child of B'Elanna Torres and Tom Paris, who had been conceived fourteen to fifteen weeks prior. (VOY: "Prophecy")
In the year 2379, The Doctor developed a treatment that would allow Kes to extend her life beyond the short natural lifespan of a normal Ocampa. The bio-temporal chamber he created had the side effect of placing her in a state of temporal flux, transporting her to different time periods throughout her life, including the moment she was conceived. (VOY: "Before and After")