I'm a retired Anesthesiologist, can I be a...?

I'm 45 I retired two years ago but want to work again. When I was in college I had difficulty thinking if I should be an Anesthesiologist or an Obstetrician. Since I knew nothing of childbirth from experience I went ahead and became an Anesthesiologist. Is there any way I can become an Obstetrician now at my age?