Q: Is it normal for my 4-month-old to suddenly stiffen his body and grunt?

This post is a dramatization of a question and answer session experienced by our actual medical reviewers. Please note that this content is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.

Q: Help! My 4-month-old son has started doing this weird thing out of nowhere. Whenever I lay him on his back while he's awake, he starts grunting and straining really hard. He’s a happy, healthy baby, but for the last day or so, he’s been clenching his little fists, stretching his legs out completely straight, and they even lift off the mat a bit. A couple of times, he even lifted his hips up. It barely happens when I'm holding him, which is strange. Of course, I made the mistake of googling and now I’m terrified about Infantile Spasms. He doesn't seem sick or in pain—he's his usual smiley self otherwise. It just seems to happen mostly when he's flat on his back. Could this just be him discovering his muscles or something? Or is it something more serious? 😟

A: That grunting/stiffening is super common at 4 months! Often just exploring muscles, gas, or prepping for a poop. Also good catch on the hip elevation – sounds different from a typical 'jackknife' spasm. Still, best to be sure.

It's best to try and get a video of it; it'll totally help your pediatrician make an assessment. That's the clearest way for them to see what's happening and give you peace of mind.

For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.

https://fevercoach.us