It depends.My parents got their visas twice for helping

me take care of the babies. I wrote in my invitation letters that I was pregnant and would like my parents to help me when my maternity leave is over and go back to work when I had both of my children and they got their visas. I think it depends on your materials-affadavit of support, bank statement, stable job and your parents' income, housing, medical and other family members in China