Fourth Trimester..

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Your baby's fourth Trimester starts from the moment she's born and lasts until she is three months old. The term is used to describe a period of great change and development in your newborn, as she adjusts to her new world outside your womb. You may find the term “trimester” odd, since your baby is already born..
You can look it up if you would like to know more about this or for tips.