Which form of birth control is injected every three months to remain effective?

The "birth control shot" is injected every three months (or 12-13 weeks) in order to remain effective.

The shot injects a hormone called progestin, which can prevent ovulation, so therefore, sperms cannot fertilise an egg because there's no egg released from the ovaries.

However, this method of birth control does not prevent people from getting STDs, so, doctors also recommend couples to practice other barrier birth control methods like condoms in order to prevent themselves from getting STDs.

gametes or germ cells are haploid cells (example: sperm and ova) containing only one set (or n) number of chromosomes and autosomal or somatic cells are diploid cells containing 2n number of chromosomes.