Your 5-month-old: Week 3

How your baby's growing:

Your baby's getting better at spotting very small objects and tracking things that are moving. At this point, he may be able to recognize an object after seeing only part of it — like his favorite toy peeking out from under a blanket. This will be the basis of little hide-and-seek games you'll be playing in the coming months. He can also follow an object out of his view.

You may also notice that he'll reach for a block (or another object) on a table if you hold him close to it, and once he's got one, he may just go after a second.

• Learn more fascinating facts about your 5-month-old's development.

Your life: Using a babysitter

Starting to use a babysitter is a big decision. Perhaps the hardest part is finding and choosing someone you like and trust, especially if family members or close friends are unavailable. Asking friends, neighbors, and other new parents for references is a great way to locate candidates. Some areas have babysitting agencies through which you can hire a prescreened candidate. Or try the student employment office at a local school or college.

Another option is to swap babysitting time with another parent or couple. Babysitting co-ops are larger, more formalized organizations in which a group of parents take turns sitting for one another's kids.

There are a number of important factors to consider when choosing a babysitter, including age, experience, and knowledge of infant CPR and first aid. Asking for references is a good start, as is a thorough interview to help you gauge the sitter's character, personality, and qualifications. Watch the babysitter interact with your baby, too. A preteen or teen who may be too young to be left alone with your baby could be hired as a "mother's helper" — someone to help watch the baby while you work or do jobs around the house.

Once you choose a babysitter, it's wise to ask her to come a little early so you can spend time together. Let her hold your baby while you prepare her by going over your baby's routines. Give her all the important information: contact numbers for getting in touch with you and your baby's doctor, an escape route from your home, the location of first-aid and emergency supplies, your baby's medical information, and healthcare authorization in case you're unavailable. In terms of compensation, it's a good idea to ask other parents in the area what the going rate is.

3 questions about: Growth charts

Why do doctors monitor babies' growth over time?
Your baby's doctor looks for an overall growth pattern by measuring your baby's weight, length (or height), and head circumference and comparing it with both national averages and previous measurements. Sudden deviations from this pattern or extreme measurements may indicate a problem with taking in or absorbing nutrients, an illness, or a developmental problem. Use our growth percentile calculator to see how your baby compares to his peers.

What do "percentiles" mean?
Your baby's doctor will tell you that your baby ranks at a specific percentile on a growth chart. It's a way of comparing your baby with the full spectrum of babies nationally. If your baby is in the 25th percentile for weight, for example, this means that 25 percent of babies the same age and gender in the United States weigh less and 75 percent weigh more. Growth percentiles between the fifth and 95th are considered normal.

What if my baby seems ahead or behind?
Don't worry too much if your baby isn't close to average size (i.e., the 50th percentile). Your baby grows at an individual pace. Growth spurts may have him speeding up the chart one month or one year and then leveling back the next. Some babies are naturally larger or smaller because of their genetic background. Another reason not to fixate on a number on a growth chart is that your baby's well-being involves a variety of factors, including development, temperament, and activity level, not just growth. If you have concerns, talk to your baby's doctor and she'll be able to tell you whether there's anything to be concerned about.