Why the internet claims Alia Bhatt is 5 months pregnant?

After Alia Bhatt's Pregnancy announcement, fans are thrilled to know everything about the pregnancy. Recently the actress came back to Mumbai from London after completing her Hollywood debut "Heart of Stones" and people noticed her baby bump at the Mumbai airport. Many people are assuming that the actress has been pregnant for the past 4-5 months as Alia didn't mention how long she's been pregnant for. What do you guys think?