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The New Sibling Regression: Aggression & Defiance

The New Sibling Regression: Aggression & Defiance

By Amalah


I need some help distinguishing between normal toddler behavior and worrisome behavior. My daughter just turned 3 (and boy, is she good at it!) She has always been a high energy, affectionate child. And most of the time that is still true. But lately, she has become defiant and occasionally aggressive. She will outright defy me when I ask her to do/not do something. This happens probably 1-2 times per day. And sometimes she hits her baby brother. Not hard enough to hurt him (he can sleep through it.) This happens when I tell her something she doesn’t want to hear, like “it’s time for bed” or “no, you can’t have Cheetos for breakfast.” It doesn’t seem like she is trying to hurt him…she seems like she is just overwhelmed by her emotions. She loves her brother and dotes on him usually, and always apologizes, but this behavior is so out of character for her. (And obviously I keep a close eye on the baby to make sure he doesn’t get hurt.)

I know that some of this is normal and that she is testing boundaries. But I want to make sure that I’m not missing something more serious.

As for how we handle this, my husband and I have tried to ignore the tantrums and defiant behavior as long as it’s not dangerous. If she is being disruptive, we calmly take her to her room to “take a break” and ask her to rejoin the family when she is “feeling better.” When she hits, we take her to her room and tell her she can rejoin the family when she can treat everyone nicely.

We have had some big changes around here lately, so I know that could be part of it. I have a 4 month old baby, so she is no longer the baby of the family. I was home for maternity leave, and just went back to work a few weeks ago. Same with my husband – he was off for about 8 weeks then went back to work. And it does seem like these outbursts are worse when she is tired, hungry, etc.

I guess I’m looking for either reassurance that this is all normal and will pass, or someone to tell me that this behavior is a red flag that I need to address further. Sorry this is so choppy and rambly- between the nighttime wake ups with the 4 month old (we’ll save that for another letter!) and worrying about the 3 year old, I’m exhausted and probably not totally coherent.

-worried mama


Normal normal normal.

Okay gang! That’s all the advice I have for today, see you next time.

Just kidding, but seriously. There is not a single “red flag” to be found here. Just a typical toddler mishmash of testing boundaries, poor impulse control, the new sibling regression period, Mom and Dad were home and now they’re not, and also just plain old Being 3 And Good At It.

I totally know how you feel though, and why it can seem so worrisome. After I had my second baby there were literally days when I would look at my oldest (who was also 3) and be like, “oh my God, I have BROKEN MY CHILD.” He was so inexplicably difficult and demanding and defiant in the months after his baby brother (who he also loved!) arrived. And we didn’t even have the whole maternity leave/going back to work upheaval. (Although he did have his dad and grandparents home with him quite a bit, and then they left and WATCH OUT MOM I’M A HANDFUL.)

The “new sibling regression” is usually rooted in attention-seeking behaviors, and most toddlers default to seeking NEGATIVE attention. Because that’ s honestly easier — we get tired or distracted with the new baby we forget to praise them the way we used to, but sure as HELL are going to react when they hit the baby or throw a toy at our head. We give them a big dramatic response and in their minds, this is a win because it’s attention. And they’ll take it because they’re feeling jealous and insecure.

The key is to fight negative attention with positive attention. Praise her when she’s being gentle with the baby. Make a fuss over how nicely she’s sitting at the dinner table or for remembering to put her clothes in the hamper. If she isn’t actively misbehaving, find something positive to focus on and praise her for.

And whenever possible, try to arrange one-on-one time with her (your husband too). Special weekend outings are great — they can be simple like going with Daddy to the grocery store and getting to “help” and pick out something special for herself. You leaving work a little early (or going in late) so you can take her to a playground or out to breakfast while her brother is in childcare. A one-on-one trip to the park, etc. Just little ways to reassure her that she’s still special and deserving of your positive attention.

When the tantrums hit, continue to ignore them. If bedtime or other transitions are a consistent trigger for them, be sure to give her a couple warnings (10 minutes, five) before the abrupt “okay time for bed!” type announcements. When she hits her brother, put your attention on HIM. “Oh, are you okay? Poor baby, etc.” Give the child who got hit the attention and pretty much ignore the child who did the hitting. This will teach her that hitting doesn’t serve her purpose of getting that immediate reaction from you. After lavishing the baby with your attention and concern, you can then enforce consequences. (Believe me, you’ll be using that method for a long time. I still do. Welcome to siblinghood!)

I also suggest changing her time-out venue. Kids’ rooms, in general, aren’t always the best cool-down spots in the house. They’re full of toys and books and visual stimuli. Plus you can inadvertently trigger bedtime issues if you’re using the place where they sleep as a “punishment” during the day. I would try time-outs somewhere she can actually calm herself without a ton of distractions. We usually use the “naughty step” timeout for aggressive stuff like hitting or throwing toys (no more than one minute for each year of their age), and offer a “cool down” spot for the tantrums borne of frustration/tiredness/hunger/thirst. Think a small tent or fort, a hammock swing, one of those chairs from IKEA with the pull-down cover, etc. After she’s calmed down, time permitting, you can join her for some loving, positive attention — read a book, bring her the snack/drink she needed but forgot how to use her words, etc.

Now, if her level of defiance and aggression remains “worrisome” even after a concerted, sustained effort to do everything listed above, and if enough time passes that the daily, ongoing defiance is no longer tethered any big recent changes (like another 6 months)…you CAN consider getting her evaluated for a possible disruptive disorder. Again, I REALLY REALLY don’t think that’s what’s happening here, but as I’m not a developmental expert, I admittedly am not the final word on sussing out normal adjustment issues vs. behavior problems tied to something like Oppositional Defiance Disorder. So if your mom-gut continues to nag that “something else is going on here,” there’s absolutely nothing wrong with finding a child therapist or psychologist (preferably CBT-focused) for a proper evaluation.

Good luck! Just because this is all mostly likely “normal” doesn’t mean that it’s a bunch of puppies and rainbows to deal with on a daily (sleep-deprived) basis. It will pass, and while there are things you can do to “help,” there’s no real reason to get too worked up and worried about it. She’s 3. Someday she will be 4!

(Meanwhile I’m counting down the days until 5, oh my lands.)

About the Author

Amy Corbett Storch


Amalah is a pseudonym of Amy Corbett Storch. She is the author of the Advice Smackdown and Bounce Back. You can follow Amy’s daily mothering adventures at Ama...

Amalah is a pseudonym of Amy Corbett Storch. She is the author of the Advice Smackdown and Bounce Back. You can follow Amy’s daily mothering adventures at Amalah. Also, it’s pronounced AIM-ah-lah.

If there is a question you would like answered on the Advice Smackdown, please submit it to

Amy also documented her second pregnancy (with Ezra) in our wildly popular Weekly Pregnancy Calendar, Zero to Forty.

Amy is mother to rising first-grader Noah, preschooler Ezra, and toddler Ike.

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  • Felicity Marie

    April 25, 2016 at 4:50 pm

    Hey, psychologist here. Just wanted to echo Amy’s comment that this is all SO normal. Everything she recommends doing, and everything you and your husband are already doing, is great. Adjusting to a new sibling is so very hard for everyone.

    I wanted to comment on the possibility of evaluating for oppositional defiance – she’s just too young. I would never diagnose a 3- or 4-year-old with it because all preschoolers are defiant. So please go ahead and set that to the side for now. If her behavior is worrying you six months from now, sure, find a good therapist to meet with her for some play therapy. But if that therapist wants to diagnose your 3-year-old with a behavioral disorder, I’d be wary. 

    Good luck!

    • Isabel Kallman

      Isabel Kallman

      April 25, 2016 at 4:56 pm

      Thanks so much for your insight and taking the time to share your expertise.

  • Autumn

    April 26, 2016 at 12:26 am

    I have a 4 1/2 year old and an almost 10 month old.  Totally normal on the defiance.  Sucks, but normal. . .  We do time outs in our entry way cause way boring! 

    What does help in addition to Amy’s advice is me telling the baby “just a minute, I’m helping big sister right now”  That way big sister hears me say I’m helping her, while hearing baby cry (not freak out distress cry, just fussing)  So it’s not every time baby cries she gets mommy attention immediately, or at least how I hope the big kiddo perceives it

    Our other thing which seems to help behavior wise is big kid gets to choose who helps with bed time.  As I’m still nursing, its a timing challenge if she chooses me, but it lets her have that “mommy” time she wants

    • Kate

      April 27, 2016 at 2:21 pm

      Yep, boring is the key. We always had time out on the stairs when I was growing up for exactly that reason. 

  • SarahB

    April 26, 2016 at 1:39 pm

    Two words: Daniel Tiger.

    It’s the best for teaching three year old’s how to handle their feelings–and to teach parents how things appear to the three year old!

    • Meagan

      April 27, 2016 at 2:06 pm

      We love Daniel Tiger too! It’s a wonderful show for preschoolers, but also for the early elementary set if there are any developmental delays.

      • Kate

        April 27, 2016 at 2:23 pm

        My 6 (almost 7) year old is on the spectrum and he still happily watches Daniel Tiger with his younger siblings. There’s even a series of episodes about having a new baby in the house now which is great. That being said I’m pretty sure the reason my 4 year old growls when she’s frustrated is because that’s what Daniel does 😉 .

        • momofa16yearoldandtwoyearold

          April 29, 2016 at 1:37 pm

          Lol- my two year old growls and says I’m mad and I totally blame Daniel Tuger.

  • IrishCream

    April 27, 2016 at 10:27 am

    My three-year-old is almost four, and she’s the little sister–no life changes, no trauma, she’s just occasionally a huge a-hole for no reason. (I say that with love and understanding, but man, she can be a jerk.)

    She would never dream of hitting in daycare, or hititng a friend, but at home she is done, her resources are exhausted, and when she gets mad, she’ll start swinging. What has helped us mitigate her behavior somewhat: identifying the triggers.

     The end of the day was a hot spot, when everyone gets home from work/school/daycare. Now, I take a pause before I start cookinng, and do a three-minute snuggle time with her. That’s eased the transition and has led to fewer tantrums. And when she does hit, we ignore it as much as possible. She’s doing it for attention, so she gets a bland “hands are not for hitting” and we just keep doing what we were doing (removing her big sister from the line of fire, as needed.)

  • Karen

    April 27, 2016 at 2:41 pm

    Does anyone remember the AskMoxie blog posts about age 3 and how she would talk about three being the nadir of human existence? Am I dating myself? 

  • Caro

    April 29, 2016 at 12:28 pm

    I usually agree with everything Amy says but here are some other ways to do things. 

    First, instead of ignoring tantrums, acknowledge feelings.

    And there is plenty of current research showing that time outs are not the solution.

  • Bria

    April 29, 2016 at 12:31 pm

    Thanks for the timely post! I’m due in a month with our second, and our oldest is also very, very good at being three. Hopefully we can start some of this now (better positive reinforcement, better time out/cool down spots) to train OURSELVES before the baby arrives. Thank you thank you!