Check if a string variable has an integer value

Complementing Styxxy's response, if you dont need a result just replace it by vbNull:

If Integer.TryParse(childAge, vbNull) Then

A very simple trick is to try parse the string as an Integer. If it succeeds, it is an integer (surprise surprise).

Dim childAgeAsInt As Integer
If Integer.TryParse(childAge, childAgeAsInt) Then
    ' childAge successfully parsed as Integer
Else
    ' childAge is not an Integer
End If