High levels of bloating in the first trimester (often as early as weeks 6–10 ) can make rigid waistbands feel painful or restrictive.
You can no longer comfortably button or zip your regular pants, or you find yourself unbuttoning them after every meal.
Your baby bump is starting to peek out from under your shirts or noticeably stretches the fabric of your pants.
When did you start wearing maternity clothing? : r/BabyBumps