During a vaginal birth, there is extreme distension of the muscles of the pelvic floor. Therefore, the pelvic floor is very limited in its function, or unable to function at all, during the postnatal phase. During the first 6 weeks, your body goes through an automatic regeneration process, and after that you should strengthen your pelvic floor with special postnatal regeneration exercises.
That means: it is normal that your trackle doesn’t stay in place as well as it did before birth. However, with postnatal exercise, your pelvic-floor muscles can regain their strength. We recommend discussing postnatal exercises with your midwife.