As a personal observation from both my wife and I,
1) Family and friends who were on the pill from say the time they were 16 or so and then tried to have children in their early 20’s to mid 30’s lost many to miscarriage before success, or had no success at all.
Others like ourselves (and there were only a handfull) never used hormone altering birth control and we all had an easy time of conception (way easy :>)
There was a study out in the past few years which claimed the birth control pill over time trained the body like a vaccine to become immune to pregnancy. This probably accounts for the large increase in fertility treatments for women, especially in young women.