He waited in his car outside as she was seen by medics who learned she was pregnant, Ascension Parish Sheriff’s Office spokeswoman Allison Hudson told the local media.
But following further investigations, hospital staff began to suspect Sanchez was the father, according to the Daily Star.
Staff alerted police to the location of the alleged rapist, but by the time police arrived he reportedly abandoned his car and left on foot.
Police found the man curled up on a patio carrying narcotics, marijuana and drug paraphernalia, they said.
He was arrested and booked into Ascension Parish Prison on a range of felony charges including first degree rape with a victim under 13, criminal trespass, illegal use of a dangerous substance controlled in the presence of a person under 17 years of age, resistant to an agent and various other counts of drugs, goods and trafficking.
His bond was set at $ 340,000 (£ 260,000).
The age of consent in Louisiana is 17, as in most states where the age ranges from 16 to 18.
Under Louisiana statutory rape laws, if the accused is more than four years older than the victim, or if this is the accused’s second (or subsequent) conviction, then the crime automatically passes from a misdemeanor to a crime.