When you're giving birth, it's valuable to have an experienced person there to be with you the whole time assisting and advising. In a hospital setting the professionals attending the birth generally have lots of patients and other responsibilities they need to be dealing with, and can't be there all the time. A doula is a non-medical professional who assists the laboring mother and provides continuous support through the process. On average women laboring with the support of doulas have shorter labors, fewer Cesarean deliveries, rate the experience better, and their babies have higher apgar scores. Despite these benefits, insurance companies generally won't pay to have a doula present during labor. Which made me wonder: would paying for people to have doulas be cheaper for insurance companies on the basis of the decrease in C-section rates alone?
Some rough looking online suggests most doulas charge between $400 and $1000. On average private insurers pay out $18,329 for a vaginal birth and $27,866 for a Cesarean.  In one randomized controlled study of providing doulas at hospital births (n=420) they found that the C-section rate dropped from 25% to 13.4%.  Naively combining these figures, current hospital practice costs insurers around $20.7k per birth  while providing doulas would bring average costs down to $19.6k . This isn't a huge difference, but at $1100 it's enough more than a doula would charge for the insurer to come out ahead.
Cost is definitely not the only thing we should consider in determining what medical care someone should get, but when something not only provides benefits but also reduces costs it seems like a clear choice.
 The Cost of Having a Baby in the United States (Truven Health Analytics, 2013). Truven maintains a medical database, MarketScan, which has cost information for various medical procedures. It's not fully clear how they get their data and seems to involve lots of agreements with employers to share claim results, but the New York Times seems to trust it.
 A Randomized Controlled Trial of Continuous Labor Support for Middle-Class couples: Effect on Cesarean Delivery Rates (McGrath and Kennell, 2008). They randomly assigned 420 women giving birth at a hospital to have a professional doula present or not. Of the ones with doulas, 13.4% ended up getting C-sections while of the ones getting conventional care 25.0% did.
 $27,866 * 25.0% + $18,329 * 75.0% = $20,713
 $27,866 * 13.4% + $18,329 * 86.6% = $19,607