So there's this girl..

This girl I'm friends with on facebook lost her baby at 17 weeks 3 weeks ago. She delivered her and everything.. Since then shes constantly posted stuff on Facebook about not being ready to try again and posting pictures of miscarriage stuff mourning her daughter. This I understand completely. Ive lost babies so I know everyone copes differently. But today she posts, 3 weeks later guys, that she's pregnant again. How is this even possible? Did she have sex the same day? Idk something seems off to me...