It's normal for babies to get sick now and then, but if their signs and symptoms gradually worsen or simply persist over a couple of days, do not hesitate to contact the doctor. Below are signs and symptoms that require medical attention:

Changes in your baby's appetite

If your baby refuses two consecutive feedings, contact your doctor. Also, if your baby becomes lethargic when sucking the breast or bottle or has difficulty feeding, tell your doctor right away.

Changes in your baby's mood

If your baby is lethargic or unusually difficult to rouse, talk to your doctor right away. All babies — newborns in particular — normally go through fussy times during the day or before bedtime. However, if your baby is persistently irritable and inconsolable, he or she should probably see a doctor. As a general guide, if a crying jag has lasted three hours and it shows no signs of letting up, a call to the doctor is in order. If your gut feeling says that your baby is ill or in pain, call sooner.

Changes in your baby's skin color

Many newborns develop jaundice, a yellowish discoloration of the skin, during the first few days or weeks of life. Newborn jaundice usually goes away in a couple of weeks as your baby's liver fully matures. However, if your baby's skin takes on a deeper yellowish hue after remaining only slightly yellow for a few days, contact your doctor immediately. The reappearance of newborn jaundice a few days after the condition has seemed to resolve also is cause for concern. Likewise, if your baby develops jaundice after having normal, pinkish skin for his or her first few weeks, call your doctor.

Fever

Don't panic if your baby (older than 2 months of age) develops a mild fever — it's common and usually isn't dangerous. To be on the safe side, call your doctor right away if your newborn (younger than 3 months) has a temperature of 100.4 F or more, or your older infant has a temperature of 102 F or above. A temperature of 102 F or above in a baby over 3 months old may or may not warrant an actual office visit, depending on the symptoms accompanying the fever.

Diarrhea

It's normal for breast-fed babies to have soft stools. However, if your baby's stool is loose or watery for six to eight diaper changes, you should get in touch with your doctor.

Vomiting

All babies spit up occasionally and some spit up more than others. However, if your baby begins to spit up a large portion of every feeding, or if he or she begins vomiting forcefully, call your doctor.

Dehydration

This is a serious side effect of diarrhea and vomiting, especially among infants, and it warrants an immediate call to your doctor. Signs include failure to urinate (no wet diapers) for six hours or longer, sinking of the soft spot on top of the baby's head, or dry lips and no tears.

Constipation

You are the best judge of the normal frequency and quantity of your baby's bowel movements. If your baby suddenly cries during a bowel movement, passes bloody or jelly-like stools, or has fewer bowel movements than usual for a few days, contact his or her doctor.

Upper respiratory infections

It's normal for an infant to catch an occasional cold. However, if your baby has a cold that interferes with breathing or feeding, or if the cold is accompanied by severe coughing or discolored phlegm, contact your doctor.

Ear pain

Babies sometimes get an ear infection after they've had an upper respiratory infection. Pulling at an ear and failing to respond to sound are signs to watch for. A baby with an ear infection may also have a fever or, less commonly, ear drainage. If you notice these signs and symptoms, call your doctor.

Cord or circumcision infection

Newborns' umbilical cords and circumcisions should heal within a couple of weeks after birth. Contact your doctor if your newborn's umbilical area or penis suddenly starts to swell, ooze or bleed.

Rashes

Localized rashes, such as diaper rash or eczema, are common among infants and can usually be treated with over-the-counter diaper ointment. However, if a diaper rash or patch of eczema becomes red and raw, call your doctor. Also call your doctor if your baby suddenly develops an unexplained rash or a full-body rash accompanied by a fever.

Eye discharge

A red, swollen eye with yellowish-green discharge may signal a blocked tear duct or conjunctivitis (pinkeye), both requiring a visit to the doctor for treatment.

Minor injuries

As your baby gains mobility, he or she will become more accident-prone. Anytime your baby gets a minor cut, bruise or burn that you're unsure about how to treat, call your doctor for advice. A good rule of thumb: Bruises should not occur before a child walks.

As a general rule, trust your intuition. If you think you should call the doctor, call. If you think you should take your baby to the emergency room, do it. When it comes to your baby's health, the old adage "Better safe than sorry" is true.