The Development of an 11-Week-Old Baby

Your 11-week-old baby is approaching 3 months of age and is beginning to move more frequently and show his personality. Although every baby develops at his own pace, there are some basic milestones you can watch for and ways that you can encourage his development.

Growth and Physical Development

KidsHealth states that your baby will grow about 1 to 1.5 inches a month, although this amount may be different if she was born premature. Your baby’s doctor will measure her at regular check-ups to make sure she is growing properly. She wets approximately four to six diapers a day and has regular bowel movements. While she is on her tummy, she is able to push off with her legs while she works to strengthen her muscles. You may also notice that her movements are becoming smoother.

Social Development


Development of a 10-Week-Old

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Your baby’s social development is noticeably improving. He may smile at people and hold out his arms when you go to pick him up. He will also respond to you more with smiles and babbling. According to BabyCenter, now is a good time to introduce him to new people or caregivers, because he is not yet experiencing separation anxiety.

Language Development

Although your baby is still a few months away from being able to talk, she can still vocalize things. She cries to communicate her needs, and is beginning to babble and make sounds. During this time, you may begin to notice her personality emerging through her voice and her ability to laugh out loud.



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Your baby will sleep 16 to 20 hours a day at this age, according to KidsHealth. Ten of those hours will probably be at night, although he only has the ability to sleep six to eight hours in a row without needing to eat. To get him to fall asleep easier at night, this is a good age to establish a regular bedtime routine that consists of calm activities such as a bath and bedtime story.

Encouraging Development

To encourage the growth and development of your 11-week-old baby, BabyCenter recommends that you give her plenty of space to stretch out and use her muscles. Talk to her regularly while making eye contact, and allow her to respond to you with babbling. Move her legs and clap her hands together to help her discover how to move.