Dear Dr. Dad: Our 11-month old daughter used to be so sweet and good-natured. But she’s recently started biting and hitting everyone. What can we do?

Answer: Right around their first birthdays, almost all babies go through a phase when they bite and/or hit people – strangers and loved ones alike. If (when) your baby starts, the first thing you need to do is find out why. Your baby may be biting or hitting because she’s:

• Trying to express affection (you probably nibble gently on her and she may simply be trying to imitate you).

• Frustrated that she can’t express herself verbally.

• Teething and trying to relieve her discomfort.

• Simply conducting an experiment to see how others will react.

• Tired, overstimulated, or frustrated.

• Trying to defend herself or her property.

• Imitating an older friend or sibling.

Fortunately, the hitting-and-biting phase usually lasts no longer than a few months.

Here are a few dos and don’ts that may make this painful period a little shorter:

• Don’t get angry.

• Don’t slap or spank.

• Don’t bite back or have the baby bite herself “to show her what it feels like”; this sets a rotten example and will only reinforce the behavior by implying that it’s really OK.

• Do remove the baby promptly. If she’s sitting on your lap and bites you, put her down for a minute (no longer); if she’s hit or bitten someone else, take her away from that person for a minute.

• Don’t say, “You’re bad” or any variation on that theme. Instead say, “Biting is bad.”

• Don’t overreact. The baby might find your reaction so amusing that she’ll bite or hit again just to get your attention.

• Do spend some time trying to figure out why your baby is biting or hitting. Is it happening at certain times of the day (right before nap time, for example)? Does she do it only to certain people?

• Do rethink your discipline policies. You may be setting so many limits that your baby may be trying to bite her way to freedom.

Armin Brott is the author of many best-selling books on fatherhood. His new DVD, “Toolbox for New Dads,” has just been released. You can find out more about it and Armin’s other resources for fathers at www.mrdad.com or by emailing arminmrdad.com. Try DaddyCast, his new, twice-weekly podcast (http://www.mrdad.com/daddycast.