Okay, this one is sort of true. While Mrs. Kennedy did have a stillbirth while her husband was in office, Mrs. Lincoln's son Willie died of typhoid at age eleven. So while both women lost children while living in the White House, they both did not die during childbirth as the statement implies. Both Presidents were shot on a Friday. Friday is the first day of the weekend.
Most public events happen on weekends.
Both presidents were attending public events. Both Presidents were shot in the head. There are only two places where a gunshot almost assures death. The head and the chest. Considering where the shooters were in comparison to their victims, the head was the likely choice.