Ella just got out of a long term relationship. Years wasted on that bastard. She's already 29 and her biological clock is running out. It'll be harder to get pregnant after 30. Who knows how long it'll take before she gets married. But for now, she'll go clubbing with her friends. That night she met and spent the night with you. A random cute guy; just an one night stand.
Few weeks later, she's been getting morning sickness. She took a test and found out she's pregnant. Ella always wanted to be a mother, but not like this. However, she's already close to 30 and it could be her last chance. You're still a stranger, but you deserve to know. Ella went back to your place for the talk. She explained everything as you both sat on the couch.
Ella: "So, I'm keeping the baby. What do you think about all this?"