4 Month Old Baby Milestones

Keep an eye on everything within Baby's reach because she'll start developing quicker reflexes. With new hand skills and rolling movements in her repertoire, she'll be busy exploring her environment during her fourth month of life.

What to Expect in the Fourth Month

"Babies will begin to reach out and take something" at 4 months old, says Kenneth Wible, M.D., medical director of the Pediatric Care Center at Children's Mercy Hospitals & Clinics in Kansas City, Missouri. "Their hands should be fully open and they should be able to reach out and grasp things, and they will begin to bring [things] to their mouth."

Most babies will sit with support at this age, and they'll enjoy standing upright with support as well, Dr. Wible says. But the most exciting 4 month baby milestone is perhaps rolling. "Rolling is significant because it's the beginning of the skills of locomotion that move baby from one place to another," says Donna Eshelman, a movement specialist and founder of Stellar Caterpillar, a Los Angeles-based business that helps babies reach their gross motor milestones in the first year.

Even so, many of your baby's movements are the same as they were in the third month. "But there's a lot more strength in them and they're doing them more easily," Eshelman says. "They're also lifting their head much, much higher."

What's more, your 4-month-old will no longer rely solely on you for entertainment—in fact, he might enjoy a little independent playtime. "They'll begin to entertain themselves," Dr. Wible says. "If you leave them on their back, they might grab their feet or fingers and stick them in their mouth. If there's a toy, they'll shake it and taste it."

Your baby's vision has also improved at 4 months old. Her eyesight is probably 20/40 or 20/50, and she can tell the subtle difference between shades, Dr. Wible says. "That's why it's sometimes difficult to feed a 4-month-old—because [he's] looking all around the room," he adds.

Let your doctor know if Baby isn't reaching for objects by the end of the fourth month, since it could indicate a problem with vision or motor development.

How to Help Baby Development

Extend the length of tummy time during the fourth month of life. "At this time, babies have enough strength to keep their head up and play with something. They also use their hands a little bit more during tummy time," Eshelman says.

Your baby might be also manipulate bigger and heavier toys by the end of this month. "There's a lot more engagement of their arms and hands, so provide toys that have different textures and different sizes, as well as toys that invite discovery," Eshelman advises. Soft books and sound-producing toys can reward a baby's curiosity.

The fourth month can also be a good time to introduce swimming, Eshelman says. "When babies are in the water, they can meet milestones much earlier than when they are on land," she says. "They love it. It's a great way to strengthen their muscles, especially the legs."