At prenatal classes, I often asked expecting parents to list the differences between 4-day-olds and 4-month-olds. Many of the first-timers thought it was a silly question and would laughingly say, “Ha! Not much! They’re all little babies.” But the experienced parents would pipe up and say, “You have no idea!” 

Newborns are beautiful, but their abilities are quite limited. Four-day-olds can barely coo or turn their heads to see who’s speaking. By contrast, 4-month-olds’ delicious smiles and glowing eyes reach out like a personal invitation. 

Months and months may pass in our lives without a whole lot of change. But during the first four months of life, your baby will make amazing leaps in development. While all babies are unique and may not all hit milestones at the exact same time, here are some big leaps to expect between day four and month four: 

Developmental Leaps in Sensory Abilities 

At 4 days…

  • Focuses on faces 8 to 12 inches away
  • Loves looking at red things and light/dark designs
  • Begins to recognize your scent and the sound of your voice
  • Easily focuses on people across a room

At 4 months…

  • Quickly turns head to see you or find out where a voice is coming from
  • Easily recognizes your face and starts noticing when someone is a stranger 

Developmental Leaps in Social Abilities 

At 4 days…

  • Watches you with interest, but doesn’t try to participate
  • Attracted to sounds (voices, shush, etc.)
  • Stares at faces or close objects
  • Struggles to imitate your facial expressions (such as sticking out your tongue)
  • Calmly looks around empty room

At 4 months…

  • Waits for you to stop talking before taking a turn cooing
  • Prefers human voices, especially yours
  • Face brightens when you enter the room
  • Gives a huge grin when you smile
  • Likes company, gets upset when ignored 

Developmental Leaps in Motor Abilities 

At 4 days…

  • Often crosses eyes
  • Follows slow-moving objects with jerky eye movements
  • Little ability to reach and touch things
  • Struggles to get hand to mouth (rarely able to keep it there for more than a few seconds) 

At 4 months…

  • No longer crosses eyes
  • Swiftly and smoothly follows things or people moving around a room
  • Getting better aim (may swing hand or pull off your glasses!)
  • Much better at finger-sucking, sometimes lasting a minute or more

Developmental Leaps in Physiological Characteristics 

At 4 days…

  • Hands and feet look blue from time to time
  • Body occasionally jolted by hiccups, jittery tremors, and irregular breathing
  • Little ability to lift head or roll

At 4 months…

  • No longer gets blue hands and feet unless cold
  • Rarely hiccups, never tremors, and breathing is smooth and regular
  • Easily rolls over and lifts head high off mattress (watch out for falls off the bed!)

These extraordinary weeks will speed by faster than you can possibly imagine! So enjoy cuddling and carrying your sweet newborn as you make the most of these months.

About Dr. Harvey Karp

Dr. Harvey Karp, one of America’s most trusted pediatricians, is the founder of Happiest Baby and the inventor of the groundbreaking SNOO Smart Sleeper. After years of treating patients in Los Angeles, Dr. Karp vaulted to global prominence with the release of the bestselling Happiest Baby on the Block and Happiest Toddler on the Block. His celebrated books and videos have since become standard pediatric practice, translated into more than 20 languages and have helped millions of parents. Dr. Karp’s landmark methods, including the 5 S’s for soothing babies, guide parents to understand and nurture their children and relieve stressful issues, like new-parent exhaustion, infant crying, and toddler tantrums.

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.