Linda (Sandra Bullock) works out when and where her husband dies and goes to the scene of his death when she wakes up and discovers that it's Wednesday.
When she's there, we discover that as a result of calling Jim on his cellphone and getting him to turn around, it was actually her that contributed to his death, because she asked him to turn the car around and it stalled in the middle of the road.
After he dies, we see Linda later on in life when her daughter's scars are almost gone. It is in the final few seconds of the film that we see that she is now pregnant, with the child conceived by the couple shortly before the day of Jim's death.
Thanks Richard B!