​Hospital and Time of Delivery May Affect Mother’s HealthThe risk for complications in childbirth was highest during night shifts, weekends, holidays and in July.

Compared with daytime deliveries on weekdays, the risk for complications during night shifts was 21 percent higher, on weekends 9 percent higher and on holidays 29 percent higher.

The researchers also found an increased risk of 28 percent in teaching hospitals in July, when new residents begin their training. This difference was reduced to statistical insignificance by the following June.

https://www.nytimes.com/2019/03/04/well/family/hospital-pregnancy-childbirth-delivery-complications.html