If I wait until 40 to get pregnant, how hard will it be at my age?

im a healthy person over all. My spouse is 2 years younger than me. we never thought about kids when we got together. he always have liked children but he still married me. but im afraid he might leave me for a younger woman for children.

i do want kids to be happy but i dont want to have children to keep him in my life just cause i feel threatened by age.

over all me having kids goes hand in hand and he was just neutral when he married me.

Updates
2 mo
I was the youngest in my family and my parents never expected me to have kids or get married. my family found it hard for me to have a baby. i think babies are amazing but im scared im not meant to have them.
If I wait until 40 to get pregnant, how hard will it be at my age?
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