After period 19 days what are the chances to get pregnant from precum?

Ejaculate: The fluid that is emitted prior to ejaculation usually carries some sperm and can definitely result in a pregnancy. It is impossie to give odds but in the future, if you don't want to get pregnant, you should use a condomand birth control pills.

Depends on how long: your menstrual cycle is (what day of your cycle it was). Most studies have shown low levels of sperm or no sperm in pre-ejaculate with sperm not being motile (however, don't know how promptly samples were examined). One small study published in 2011 showed that there are some individuals with a high motile sperm count in pre-ejaculate. See: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564677