“Be about + to-infinitive“ refers to arranged actions that happen in the immediate future. It is often used with “just”.
• Hurry up! The ceremony is about to begin!
• Do you have a minute? – I’m sorry, I’m just about to leave.
“Worry about“ is a verb-preposition combination that needs a gerund after it. The same as “think about”.
• I worry about having children and not being able to raise them well.
• Do you ever think about getting married and having children?