However, before a man ejaculates, a clear, colourless, sticky fluid called pre-ejaculate (also known as pre-ejaculate fluid or informally as pre-cum) can come out of his penis. Pre-ejaculate is produced by the bulbourethral or Cowper's glands. Some tests have shown that pre-ejaculate does not contain any sperm. However, some sperm may have been left behind in the urethra from an earlier ejaculation and the pre-ejaculate may carry this sperm out of the penis. That is why a woman can become pregnant even if the man pulls his penis out of her vagina before he ejaculates. Also, if a man ejaculates near the woman's vagina and semen falls on her body, sperm can accidentally enter the vagina and cause a pregnancy. To avoid the woman becoming pregnant when she does not want to, the man and the woman can use methods of contraception or birth control. For example, the man can wear a condom on his penis, or the woman can take birth control pills.