Am I Hurting My Baby by Sitting Them Up?

My mom keeps telling me I sit up my almost 4-month-old too much and that I’m hurting her bones and development. She sends me all sorts of Instagram reels from “experts” on this. What’s the truth?

—Veronica S.

You are reaching a wonderful stage with your infant. That early cycle of eating, sleeping, and diaper changes is starting to shift, and now you’re getting real awake time to play, interact, and try new things together. It’s normal and great to want to engage your baby physically at this stage.

My short answer is what you’re doing is almost certainly fine and good, although a few particulars matter.

There is no evidence or concern that short sessions of sitting your 3–4 month-old upright, with support, cause any harm to their bones or development. In fact, in my practice, I often demonstrate sitting with parents by placing the baby on a soft mat and holding them at their shoulders so they learn to support their head and neck. As they get stronger, you can move your hands down their trunk to help them strengthen their shoulders and spine, eventually holding them at their thighs or spotting them as they start to sit independently. These short, supported sessions, even done often, are not a concern.

Where sitting could potentially slow motor development is when babies spend long stretches in “containers” such as activity centers, infant floor seats, swings, or car seats outside of travel. An observational study found that increased use of “infant equipment” correlated with slightly lower motor development scores at 8 months. That sounds worrisome, but I would take it with a grain of salt.

For perspective, when pediatricians recommended back-sleeping to reduce SIDS in the 1990s, we saw delays in rolling and crawling. Yet today’s generation is no less athletic or successful. Similarly, even if container use slightly slows motor milestones at 8 months, it is not clear that it matters over the long term. I am personally skeptical that it does.

That said, if you want to give your baby the best developmental boost right now, the evidence supports giving them plenty of free time to move uncontained on their back and tummy and in a supported sitting position with you.

There is an increasing emphasis among parenting influencers (like the “experts” you mentioned) on letting infants achieve milestones independently without being placed in positions they cannot reach on their own. This is not something to be concerned about, and claims that supported sitting harms babies are not backed by any evidence.