My wife and I have three kids, 8.8 lbs, 9.7 lbs and 10.8 lbs. Wife decided after our youngest son was born that there would be no more kids, and after watching what she went through I had to agree with her.
Her obgyn was explaining to us that the average baby size in the US now (mostly due to good prenatal care and diet) continues to rise, making childbirth (especially first time mothers, who are getting older and older now) harder and harder. A 18 year old girl having a big baby is a lot easier the first time than a 30+ year old woman.
Health care has absolutely nothing to do with this study or percentages at all, a big part of it is the choices we make that reduce or increase our odds of complications.
Thats probably true but this is also bogus for other reasons.