The contraception injection was a form of birth control used in the Federation. The medicine had to be administered regularly, otherwise sexual intercourse could lead to fertilization and pregnancy.
In 2375, Benjamin Sisko, preoccupied by the latter stages of the Dominion War, forgot to renew his injection, despite repeated reminders from his CMO, Julian Bashir. As a result, his wife, Kasidy Yates, became pregnant with their child, the couple's first. (DS9: "The Dogs of War")
Background
- In The Making of Star Trek, it is stated that the birth control practiced onboard the USS Enterprise was never discussed in any episode of The Original Series because the cencors would not have allowed it. But if it would have been discussed, they would have explained contraception to be based on mothly injections mandatory for unmarried women and voluntary for married women. If a member of the crew bacame pregnant, she would have a choice between medical discharge or rotation to a shore base for the duration of the pregnancy. (pages 206, 207)
- The only reference to birth control in The Original Series was in "The Mark of Gideon", when Captain Kirk proposed to the gideons that the Federation would provide any type of devices they needed to safely prevent conception.