A Brooklyn mom went into labor in her back seat while trying to get to the hospital yesterday — but the delivery went off without a hitch, thanks to a nursing student who happened to be nearby.

Crystal Cardona’s water broke just as she got into her Nissan Altima outside her Prospect-Lefferts Gardens building around 10 a.m., sending her husband, Miguel, and other relatives into a frenzy.

“I realized — whoa! — she’s having the baby in the back seat of the car,” said neighbor Aionga Pereira, 35, a fourth-year nursing student at Long Island University.

“I’m really just happy that I did OB [obstetrics] last semester, but that didn’t take the nervousness away,” she said.

While Cardona’s husband coached, Pereira guided the head and shoulders of the baby girl.

Paramedics arrived and finished the delivery before taking mom and daughter to Methodist Hospital, where the newborn weighed in at 6 pounds, 13 ounces.