Not my story but my great grandmother's, and I was lucky enough to have her in my life until I was in my 20's, so she told me about a great many things. 
She was 49, had 9 children, and thought she was in menopause after not having a period for a year. This was in the late 1940's. Her youngest was 11, my grandmother, her eldest, was 24.
Turns out she was 6 months pregnant and not in menopause after visiting the doctor due to not feeling well. She had no pregnancy symptoms as she had with the other 9 so had no idea she was pregnant.
Her pregnancy was easy, but she did say dealing with the baby was a massive struggle at her age. She was 50 when her last, a boy, was born, My grandmother, her daughter, gave birth to my mum when this baby was 2 months old. My grandmother had already had 2 children before her mum had her last baby. My mum is two months younger than her uncle. Crazy, funny stuff.
Basically, I think dealing with an infant can be a lot harder when you're older.