In the article, she references government statistics: "[G]overnment statistics that analyze when babies are born tell the story in black-and-white: In the past twenty years the timing of births in America has shifted dramatically. Today, according to the Centers for Disease Control, the vast majority of American babies are born Monday through Friday, with a much smaller number born on the weekends."
If you want her data, email her and ask her for it.
Here's another article:
https://www.consumerreports.org/c-section/biggest-c-section-risk-may-be-your-hospital/