My mom is gonna get pregnant so I don't have an older sibling

I was born 3 years later than I should have been and therefore had no siblings, but my parents didn't do it on purpose. In the past, most people couldn't plan or choose when to have children. Until my birth, my parents would have liked to have a second child - a brother for me. However, it didn't work out because their reproductive years were already over. I understand that not every couple wants to have multiple children, and that's perfectly fine. However, I wish my parents had made a more concerted effort to have another child.