4 Month Exam:
This is an especially fun check up for pediatricians because the babies are so outgoing and social. They'll giggle and chuckle and reach out to be held. Parents can see their baby's awareness of the people around them expanding greatly. Also, the baby is usually less "fussy'" because he/she is more in touch with the environment. Babies usually enjoy outings - shopping malls, fruit stands, trips to a modern art museum are a feast for the eyes and ears.
A special note for babies of this age: When visiting relatives, a baby likes to look at the person from a distance from the vantage point of the mother or father's lap. If a grandparent comes up too close, and tries to hold the baby, he/she might cry out of disorientation. Also, when being held by a parent, if the baby is passed to another relative without realizing it, he/she might cry if he/she turns and sees a different person.
If the baby is not consolidating his/her sleep into at least one long stretch of 5-7 hours, try to address it now. The longer you want, the harder it will be. Sleep difficulties worsen as the baby gets older and more opinionated. See the article on Sleep Issues.
At four months, babies get a booster of the primary series of vaccines: DTaP, Haemophilus, Pneumococcal, Polio, Hepatitis B and Rota virus vaccines. A booster dose multiplies the antibody levels of the first vaccine. (see Immunizations and the 2 month visit article). The tylenol dose that can be given after the vaccine is 0.8mL = 80mg.
4 month Safety issues:
Babies start rolling over around this time. The most common injury in this age group is the child falling off the bed after being put down for a short time in the center of a large bed while visiting relatives. Even though a baby can't crawl to the edge, while sleeping he/she might roll over once, then twice, and eventually be at the edge of the bed. It's a good idea to make a temporary crib by boxing the baby in with a rolling barrier such as heavy books or surround the bed with chairs.
Another common scenario is the baby falling from a changing table. This usually happens with a relative who has been out of practice and forgets how quickly the baby can move.
Putting the baby in a stroller without strapping him/her in. As the baby gets bigger, if he/she starts to cry and kick, he/she can be propelled out of the stroller.
Having the baby on your lap and he/she lurches forward and gets splashed with hot coffee or tea.
This ability to "lurch" when excited makes it extremely important to keep a grip on the baby when walking up and down stairs. Don't let frail relatives carry the baby, or siblings who aren't tall or coordinated enough to break their fall in the event they slipped.
CO and smoke detectors are still of paramount importance. Also, have a "mental fire drill" when visiting relatives so you know how to get out of a house or hotel in the event of an emergency.
Avoidance of Illness:
The baby is still very susceptible to respiratory and other infections. Parents often become more relaxed than they were in the immediate newborn period. Still don't pass the baby around a room of relatives and keep the baby out of the reach of toddlers and preschoolers. (See the article of Contagiousness of Nursery School Illnesses).
Continue boiling water.
If you are handling raw eggs, raw meat or other "organic substance, wash your hands before lifting the baby.
Don't put a pacifier in a baby's mouth without quickly rinsing it with water.