# Day 342: Favoring a side, losing skills

> The don't-wait list for 12 months: pull up, wave, look for a hidden toy; one side favored; seems not to see or hear; lost skills. Early intervention is free, no referral. The both-hands day.

- Series: Your twelfth month, day by day (https://chorevia.com/learn/twelfth-month), day 342 of 365, week 46
- Canonical URL: https://chorevia.com/learn/twelfth-month/day-342
- Last reviewed: 2026-10-21
- Publisher: Chorevia (https://chorevia.com)
- Cite as: Chorevia. "Day 342: Favoring a side, losing skills." Last reviewed October 21, 2026. https://chorevia.com/learn/twelfth-month/day-342

This guide is general education that summarizes published research and guidance from groups like the American Academy of Pediatrics, the CDC, and the WHO. It isn’t medical advice, and every child develops on their own timeline. Your pediatrician knows your child; if something feels wrong, call them. In an emergency, call 911.

Most of this series has been "normal" with a call line attached. Today is the other half, said plainly: the short list of things that, at 12 months, are a reason to ask, and what to do with a worry, which is write it down and say it.

## Heart

The CDC's list for the birthday: bring it up if by 12 months your baby doesn't pull up to stand, wave bye-bye, or look for a toy they saw you hide ([CDC](https://www.cdc.gov/act-early/milestones/1-year.html)). Add to it: using one arm or leg much more than the other ([AAP](https://www.healthychildren.org/English/ages-stages/baby/Pages/Movement-8-to-12-Months.aspx)), seeming not to see or hear well ([AAP](https://www.healthychildren.org/English/ages-stages/Your-Childs-Checkups/Pages/Your-Checkup-Checklist-9-Months-Old.aspx)), and losing skills they used to have ([CDC](https://www.cdc.gov/act-early/milestones/9-months.html)). The guide's section is [Don't wait on development worries](https://chorevia.com/learn/7-12-months#dont-wait-on-development-worries). Six lines, and three of them carry a date that hasn't arrived.

## Head

CDC's checklists hold skills that at least 75% of babies show by each age, so a missed milestone is a reason to check in, not to wait and see ([Zubler et al., 2022](https://pubmed.ncbi.nlm.nih.gov/35132439/)). The checking-in costs nothing: ask your pediatrician about developmental screening, or call your state's early intervention program for a free evaluation; you don't need a referral ([CDC](https://www.cdc.gov/act-early/families/concerned.html)). Scooting and slithering count as moving: the AAP says a few babies scoot on their bottoms or slither on their bellies instead of crawling, and that's no cause for concern as long as they use each arm and leg equally ([AAP](https://www.healthychildren.org/English/ages-stages/baby/Pages/Movement-8-to-12-Months.aspx)). Equally is the word that matters today.

## Body

Sides. Many children don't show a dominant hand for years, and there's no need to push one ([AAP](https://www.healthychildren.org/English/ages-stages/toddler/Pages/Hand-and-Finger-Skills-1-Year-Olds.aspx)), so a baby who reaches with whichever hand is nearer is doing what the lists expect. A baby who reaches across their body with the same hand every time, cruises in one direction only, or drags one leg when they crawl, over days, not hours, is the one to mention ([AAP](https://www.healthychildren.org/English/ages-stages/baby/Pages/Movement-8-to-12-Months.aspx)).

## Try today

### The both-hands day

- **Time:** All day, one note at the end
- **From the guide:** [Don't wait on development worries](https://chorevia.com/learn/7-12-months#dont-wait-on-development-worries)

1. Every handoff today, alternate the side: the cup from the left at breakfast, the spoon from the right, the block from the left, and so on. Don't steer the hand; just watch which one comes ([CDC](https://www.cdc.gov/act-early/milestones/1-year.html)).
2. At the sofa, put the toy at the left end once and the right end once, and watch which way they cruise, and whether both legs step ([AAP](https://www.healthychildren.org/English/ages-stages/baby/Pages/Movement-8-to-12-Months.aspx)).
3. Call their name from behind, twice, once from each side, and watch for the turn ([CDC](https://www.cdc.gov/act-early/milestones/9-months.html)).
4. Tonight, one line in your phone, dated: "both hands, both ways, turns to name," or whatever you saw. If it worries you, that line is your question for the pediatrician ([CDC](https://www.cdc.gov/act-early/families/concerned.html)).

**Make it work:** One day's watching is a note, not a verdict. The pattern that matters runs over days ([AAP](https://www.healthychildren.org/English/ages-stages/baby/Pages/Movement-8-to-12-Months.aspx)).

## Watch for

- **Normal:** a reach with the nearer hand every time, whichever side you offer from; no dominant hand for years is expected ([AAP](https://www.healthychildren.org/English/ages-stages/toddler/Pages/Hand-and-Finger-Skills-1-Year-Olds.aspx)). **Talk with your pediatrician** if your baby uses one arm or leg much more than the other ([AAP](https://www.healthychildren.org/English/ages-stages/baby/Pages/Movement-8-to-12-Months.aspx)).
- **Normal:** a baby who cruised left all week and right today. **Bring it up** if your baby has lost skills they used to have ([CDC](https://www.cdc.gov/act-early/milestones/9-months.html)).
- **Normal:** a name called from behind and ignored for the dog, twice, and a turn the third time. **Talk with your pediatrician** if your baby seems not to see or hear well ([AAP](https://www.healthychildren.org/English/ages-stages/Your-Childs-Checkups/Pages/Your-Checkup-Checklist-9-Months-Old.aspx)).
- **Normal:** knowing this baby's two hands apart, and which one holds the spoon. **Call anyway** if your baby just doesn't seem right to you. Trust your instincts; three hundred and forty-two days have built them ([Lurie Children's](https://www.luriechildrens.org/en/blog/when-to-call-the-pediatrician-for-your-newborn/)).

## For you

A worry written down is a worry you can ask about; a worry kept in your head at 2 a.m. is a worry that grows. Tonight's line does two things: it dates the worry, so at the visit you can say "since the third week of the month," and it ends the argument with yourself about whether it counts. The list decides what counts: lost skills ([CDC](https://www.cdc.gov/act-early/milestones/9-months.html)), one side used much more than the other ([AAP](https://www.healthychildren.org/English/ages-stages/baby/Pages/Movement-8-to-12-Months.aspx)), and by 12 months, no pulling up, no wave, no search for the hidden toy ([CDC](https://www.cdc.gov/act-early/milestones/1-year.html)). If your line matches one, ask; the evaluation is free and needs no referral ([CDC](https://www.cdc.gov/act-early/families/concerned.html)). If it matches none, keep the line anyway, as the record of a worry that turned out to be a normal baby. The same goes for a worry about yourself: write the line, and if sadness has lasted more than two weeks, it goes to your own doctor without waiting for any visit ([Office on Women's Health](https://womenshealth.gov/pregnancy/childbirth-and-beyond/recovering-birth)).

If you're the partner: ask her tonight whether there's a line, and if there is, put it in your phone too, with the same date. Two phones don't lose it.

## Sources

- Centers for Disease Control and Prevention. "Milestones by 1 Year." Learn the Signs. Act Early. program, updated 2026. https://www.cdc.gov/act-early/milestones/1-year.html
- American Academy of Pediatrics. "Movement Milestones in Babies 8 to 12 Months Old." HealthyChildren.org, updated 2021. https://www.healthychildren.org/English/ages-stages/baby/Pages/Movement-8-to-12-Months.aspx
- American Academy of Pediatrics. "Checkup Checklist: 9 Months Old." HealthyChildren.org, updated 2021. https://www.healthychildren.org/English/ages-stages/Your-Childs-Checkups/Pages/Your-Checkup-Checklist-9-Months-Old.aspx
- Centers for Disease Control and Prevention. "Milestones by 9 Months." Learn the Signs. Act Early. program, updated 2026. https://www.cdc.gov/act-early/milestones/9-months.html
- Zubler JM, Wiggins LD, Macias MM, et al. "Evidence-Informed Milestones for Developmental Surveillance Tools." *Pediatrics*, 2022. https://pubmed.ncbi.nlm.nih.gov/35132439/
- Centers for Disease Control and Prevention. "Concerned About Your Child's Development?" Updated 2026. https://www.cdc.gov/act-early/families/concerned.html
- American Academy of Pediatrics. "Hand and Finger Skills: 1 Year Olds." HealthyChildren.org, updated 2009. https://www.healthychildren.org/English/ages-stages/toddler/Pages/Hand-and-Finger-Skills-1-Year-Olds.aspx
- Lurie Children's Hospital of Chicago. "When to Call the Pediatrician for Your Newborn." 2024. https://www.luriechildrens.org/en/blog/when-to-call-the-pediatrician-for-your-newborn/
- Office on Women's Health. "Recovering from birth." US Department of Health and Human Services, 2021. https://womenshealth.gov/pregnancy/childbirth-and-beyond/recovering-birth