If there is no penetration of the penis into the vagina, the chances of getting pregnant from precum (also called pre-ejaculate or pre-ejaculatory fluid) alone are very low. However, this does not apply to unprotected vaginal intercourse.
Even with withdrawal, which is when the penis is removed from the vagina before ejaculation, the chances of pregnancy are still significant. This method can fail in up to 1 in 4 couples during the first year of use. Because of this, withdrawal is not considered an effective form of birth control.
If there are concerns about the risk of an unplanned pregnancy, the safest option is to use condoms during sex or see a gynecologist, who can recommend the most suitable contraceptive method for each case. Learn more about birth control options your doctor may discuss with you.