My brother was the difficult birth. I was born right on time with a completely boring, uneventful, complication-free pregnancy and birth.
From conception till a few years after puberty, everything about my development was exactly by the book. If the baby books said that something would happen at, say, five weeks, then that something happened at exactly five weeks for me.
That said, I actually caused my mom to go into and out of labor multiple times because instead of pushing with the pointy part of my head, I was apparently using my face, but that didn't cause any problems; it just took longer before she stayed in labor long enough for the hospital to accept her.