A fussy baby can send even the calmest parent into a panic. For many parents, these mood swings are unpredictable and seemingly never-ending. That’s where The Wonder Weeks come in.

Doctors van de Rijt and Plooij claim there is a predictable pattern to fussy behavior. Using their learnings from 35 years of observational research, they have created a chart to try to predict when your baby will be fussy or pleasant, and for how long. Their conclusions are based on their observations and not on scientifically controlled studies. So don’t worry if your baby does not fit their pattern or behave in a predictable way. Not all parents find that The Wonder Weeks idea works for them.

Fussy is a relative term. Each baby’s version of fussy will be unique to them. You may also find that your baby’s fussy behaviors change over time. It’s important to remember not to compare your baby to other babies, including siblings.

For a new parent, identifying a baby’s fussy behavior may take some time, but by paying attention to the signs your baby is giving you, you may be able to identify their moods and find patterns in their behavior.

To use The Wonder Weeks chart, you’ll need to calculate your baby’s age in weeks, starting with their due date. This may be different from the day they were born. For example, if your baby was due on December 16 but born on December 20, you would calculate their age from December 16 for the purposes of using the chart.

Age in weeks from due date☺ relatively easy-going☹ fussy
0-4.5
4.5-5.5
5.5-7.5
7.5-9.5
9.5-11.5
11.5-12.5
12.5-14.5
14.5-19.5
19.5-22.5
22.5-26.5
26.5-28.5
28.5-30.5 ✓ - separation anxiety may peak
30.5-33.5
33.5-37.5
37.5-41.5
41.5-46.5
46.5-50.5
50.5-54.5
54.5-59.5
59.5-64.5
64.5-70.5
70.5-75.5
75.5-84

Keeping track of your baby’s age in weeks can be a little cumbersome for many parents. Luckily, there’s an app for that. For $1.99, you can purchase and download the Wonder Weeks mobile app. Not only can you use the app to keep track of your baby’s personalized Wonder Weeks chart, but it will also send you notifications when a fussy period, or leap, is about to start. It can provide supplemental information about the new skills your baby is learning during the current leap and what you can do to help your baby develop those skills as well.

The app provides enough information that you can use it without the book. The book provides additional information about the individual leaps plus stories from real moms, which can help you feel less alone. You can also purchase individual electronic chapters through the app.

Read more: Best phone apps every parent needs to have »

The belief behind these predictable mood swings is that babies go through development leaps at roughly the same time, and that these leaps alter the way they view their world. Seeing the world in a new way and trying to learn new skills can cause your baby to become overwhelmed, scared, or frustrated. After all, learning is hard work!

Fussy periods can often make babies clingier, too. They want the security of their parent or caregiver, because in a constantly changing world, that’s one thing that always stays the same.

You’re probably familiar with some of the big milestones, like being able to sit up or clap. The Wonder Weeks organizes milestones a little differently. Instead of focusing on a few skills, leaps are given names that relate to the shifts going on in your baby’s world.

For example, leap two, which happens around the 2-month mark, is all about identifying patterns. Leap six is about understanding categories. For each leap, there are various milestones your baby may hit. The authors stress that sometimes a baby learns the skill in one leap, but doesn’t actually utilize it until the following leap. Other times a baby may be focused on one area of development, like communication or fine motor skills. This might put the other skills on the back burner. That’s one explanation for why babies do things like walk and talk at different times.

If you are worried about your child’s development, reach out to their pediatrician. A pediatrician can tell you if there’s reason to be concerned about your child’s development and point you toward resources, if necessary.

Learn more: The activities your baby needs for development »

When your baby is going through a leap period, getting through your day can leave you feeling like you’ve just run a marathon, minus the runner’s high. Simple tasks like washing the dishes or folding the laundry can take hours. You’ll regularly have to stop what you’re doing to comfort a crying, clingy baby. To add to your exhaustion, babies sometimes wake more during the night while going through a leap, so you may be sleep-deprived.

Here are some tips to help you make the most of your baby’s leaps:

Consider wearing your baby in a soft carrier, such as the Baby K’tan baby carrier. Wearing your baby can help soothe your child without keeping you from leaving the house or getting through your to-do list. Make sure to follow the carrier’s instructions to avoid injury to your baby or yourself.

Take a time out. A 2014 study found evidence that babies may be able to sense the moods of their parent. If you become overly stressed by your baby’s fussiness, put them in a safe area, like a crib, or hand them off to another caregiver, and take a time out. Go to another room while you regroup, or if the crying is really bothering you, consider leaving the house for a short time.

Give your baby a bath, if they enjoy them. Sometimes a bath can help reset your baby’s mood, plus the warm water can be soothing.

Take your baby for a walk. A change of scenery can do wonders for baby’s mood and yours.

Experiment with new games, sounds, or textures, or retry something from the past. As your baby’s worldview changes, so, too, will their response to stimuli. That rattle they’ve barely touched may suddenly be incredibly exciting, or you can show them a new use for their lovey, like for a game of peek-a-boo.

Lower your expectations. Babies are demanding on a good day, but during a leap, those demands can be all-consuming. Put off your housework and remove nonessential things from your to-do list, or enlist a friend or family member to help you get stuff done.

Plan ahead. If you see that a leap is coming, try to get ahead of it. Consider freezing several make-ahead dinners and check as many things off your to-do list as you can. You may even want to consider putting off unnecessary outings until after a leap.

Babies are constantly changing. The world is a new, exciting, and sometimes scary place for them. As their caregiver, you can help them navigate through their development leaps. Provide stimulating, age-appropriate games and activities to help them learn new skills. Set aside extra time to get things done, and plan for extra snuggle sessions during your baby’s leap weeks. You never know, you may come to miss these clingy periods when your child’s no longer a baby.