Those innate reflexes -- such as the startle reflex that your baby displayed during the first couple of months -- should be fading or gone by now. You’ve probably also noticed that baby’s neck strength is improving. When you hold him upright, you should see very little or even no head wobbling. Three-month-old babies also should have enough upper-body strength to support their head and chest with their arms while lying on their stomach and enough lower body strength to stretch out their legs and kick.
As you watch your baby, you should see some early signs of hand-eye coordination. Your baby’s hands can open and shut, come together, swipe at colorful dangling toys, briefly grab a toy or rattle, and go straight into the mouth.
Third Month Baby Milestones: Sleep
Your 3-month-old’s nervous system is maturing, and his stomach can accommodate more milk or formula. Those changes should allow your baby to sleep for a stretch of six or seven hours at a time, which translates into a good night's sleep for you.
If your baby does wake up in the middle of the night, wait about 30 seconds before heading into the nursery. Sometimes, babies will cry for a few seconds and then go back to sleep. When you rush in at the first sound of fussing, your baby won’t learn how to fall back asleep on his own.
When the cries don’t stop and you do need to go into your baby’s room in the middle of the night, stick to the essentials. Feeding and changing should be done in the dark, if possible, and then it’s right back into the crib. Eventually, he will get the idea that nighttime is for sleeping only.
Your baby’s daytime sleep schedule should also become more routine by now. Most 3-month-old babies take a few naps of about 1 1/2 to 2 hours each day.
Third Month Baby Milestones: The Senses
Your 3-month-old’s hearing and vision are improving. Babies this age turn their heads and smile at the sound of their parents’ voices, and they love listening to all kinds of music.
Your baby will still prefer to look at brightly colored toys. That’s because sharp contrasts are easier to see. Faces are absolutely fascinating to 3-month-old babies. Look at him and he will stare back into your eyes. Your infant will also gaze intently at his own reflection in a crib mirror.