# Day 107: Head shape check-in

> Flat spots peak around 4 months and usually improve. The wet-hair check after the bath, the position swaps that help, and an hour of tummy time built from pieces.

- Series: Your fourth month, day by day (https://chorevia.com/learn/fourth-month), day 107 of 120, week 15
- Canonical URL: https://chorevia.com/learn/fourth-month/day-107
- Last reviewed: 2026-10-21
- Publisher: Chorevia (https://chorevia.com)
- Cite as: Chorevia. "Day 107: Head shape check-in." Last reviewed October 21, 2026. https://chorevia.com/learn/fourth-month/day-107

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.

Bath night is the easiest time to look at the back of your baby's head. Today: what to look for, what to change, and how the tummy-time hour adds up.

## Heart

A flat spot is common, and it isn't your fault. In a New Zealand study of 200 babies, head flattening affected 16.0% at 6 weeks, 19.7% at 4 months, 9.2% at 8 months, and 3.3% at 2 years ([Hutchison et al., 2004](https://pubmed.ncbi.nlm.nih.gov/15466093/)). This is the peak; the trend from here is toward round. Flattening doesn't affect brain growth ([AAP](https://www.healthychildren.org/English/health-issues/conditions/Cleft-Craniofacial/Pages/Positional-Skull-Deformities-and-Torticollis.aspx)).

## Head

The check takes ten seconds. After a bath, with the hair wet and flat, look down from above: the back of the head should be evenly round, and the ears should line up ([AAP](https://www.healthychildren.org/English/health-issues/conditions/Cleft-Craniofacial/Pages/Positional-Skull-Deformities-and-Torticollis.aspx)). If one side is flatter or one ear sits forward, the fixes are position swaps: alternate the arm you feed with and the end of the crib you lay your baby at, limit time in seats and swings, and work up to an hour of tummy time a day. Skip head-shaping pillows ([AAP](https://www.healthychildren.org/English/health-issues/conditions/Cleft-Craniofacial/Pages/Positional-Skull-Deformities-and-Torticollis.aspx)).In a Dutch trial of 65 babies who strongly preferred turning one way, physical therapy cut the risk of severe flattening at 6 months by 46% ([van Vlimmeren et al., 2008](https://pubmed.ncbi.nlm.nih.gov/18678802/)). Mention a favorite side, at the 4-month visit or sooner.

## Body

WHO advises at least 30 minutes of tummy time a day, spread out, for babies who aren't mobile yet, and no more than 1 hour at a time strapped into a seat or carrier ([WHO](https://www.who.int/news/item/24-04-2019-to-grow-up-healthy-children-need-to-sit-less-and-play-more)). A review of 16 mostly observational studies linked tummy time to better gross motor development and to rolling ([Hewitt et al., 2020](https://pubmed.ncbi.nlm.nih.gov/32371428/)). Pushing up onto elbows or forearms is a 4-month milestone ([CDC](https://www.cdc.gov/act-early/milestones/4-months.html)), and every minute of it is a minute off the mattress.

## Try today

### An hour of tummy time, in pieces

- **Time:** 5 to 10 minutes at a time, six to ten times across the day
- **From the guide:** [Tummy-time look-around](https://chorevia.com/learn/3-months#tummy-time-look-around)

1. After the bath, do the wet-hair look from above: round at the back, ears level ([AAP](https://www.healthychildren.org/English/health-issues/conditions/Cleft-Craniofacial/Pages/Positional-Skull-Deformities-and-Torticollis.aspx)).
2. Tie a piece to things that already happen: after each diaper change, after each feed once the spit-up settles, when you sit down with coffee.
3. Each piece: baby tummy-down on a firm floor blanket, arms forward, a toy raised slowly in front so they lift head and chest, then moved to the side they turn to less.
4. Keep a tally on the fridge. Stop each piece when they fuss, and add up the minutes at bedtime.

**Make it work:** Several short sessions count. Stay with your baby the whole time, and if they fall asleep, move them to their back in their own sleep space ([AAP](https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/The-Importance-of-Tummy-Time.aspx)).

## Watch for

- **Normal:** a slightly flatter patch on one side at this age ([Hutchison et al., 2004](https://pubmed.ncbi.nlm.nih.gov/15466093/)). **Bring it up, don't wait,** if your baby always turns or tilts their head one way; early treatment of a tight neck matters ([AAP](https://www.healthychildren.org/English/health-issues/conditions/Cleft-Craniofacial/Pages/Head-Tilt.aspx)).
- **Normal:** complaining a few minutes into tummy time and doing better with you on the floor face to face ([AAP](https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/The-Importance-of-Tummy-Time.aspx)). **Tell your pediatrician** if your baby seems very stiff, or very floppy ([AAP](https://www.healthychildren.org/English/ages-stages/baby/Pages/Developmental-Milestones-7-Months.aspx)).
- **Normal:** a doze that starts on the blanket. **Never** leave them asleep on the tummy; a sleeping baby goes on their back in the bare crib, every time ([Moon, AAP](https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/a-parents-guide-to-safe-sleep.aspx)).

## For you

Your own hour, in pieces. Nobody will hand you sixty free minutes today. Ten while the baby does a tummy-time piece beside you on the floor, ten in the shower, ten with the door shut: it adds up the same way theirs does.

Use one piece on your neck and shoulders, curled over a baby for fifteen weeks. If you had a C-section, most regular activities are back within 4 to 8 weeks ([MedlinePlus](https://medlineplus.gov/ency/patientinstructions/000624.htm)), so a stretch at the sink is yours to take. A headache that won't go away or gets worse is different: it's on the CDC's list of urgent maternal warning signs ([CDC](https://www.cdc.gov/hearher/maternal-warning-signs/index.html)).

If you're the partner: you keep the tally. Three of today's pieces are yours, and so is the head check.

## Sources

- Hutchison BL, Hutchison LA, Thompson JM, Mitchell EA. "Plagiocephaly and brachycephaly in the first two years of life: a prospective cohort study." Pediatrics, 2004. https://pubmed.ncbi.nlm.nih.gov/15466093/
- American Academy of Pediatrics. "When a Baby's Head is Misshapen: Positional Skull Deformities." HealthyChildren.org, 2022. https://www.healthychildren.org/English/health-issues/conditions/Cleft-Craniofacial/Pages/Positional-Skull-Deformities-and-Torticollis.aspx
- van Vlimmeren LA, van der Graaf Y, Boere-Boonekamp MM, et al. "Effect of pediatric physical therapy on deformational plagiocephaly in children with positional preference: a randomized controlled trial." Archives of Pediatrics & Adolescent Medicine, 2008. https://pubmed.ncbi.nlm.nih.gov/18678802/
- World Health Organization. "To grow up healthy, children need to sit less and play more." 2019. https://www.who.int/news/item/24-04-2019-to-grow-up-healthy-children-need-to-sit-less-and-play-more
- Hewitt L, Kerr E, Stanley RM, Okely AD. "Tummy Time and Infant Health Outcomes: A Systematic Review." Pediatrics, 2020. https://pubmed.ncbi.nlm.nih.gov/32371428/
- Centers for Disease Control and Prevention. "Milestones by 4 Months." Learn the Signs. Act Early., 2026. https://www.cdc.gov/act-early/milestones/4-months.html
- American Academy of Pediatrics. "3 Tummy Time Activities to Try With Your Baby." HealthyChildren.org, 2023. https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/The-Importance-of-Tummy-Time.aspx
- American Academy of Pediatrics. "Head Tilt (Torticollis)." HealthyChildren.org, 2020. https://www.healthychildren.org/English/health-issues/conditions/Cleft-Craniofacial/Pages/Head-Tilt.aspx
- American Academy of Pediatrics. "Developmental Milestones: 7 Months." HealthyChildren.org, 2009. https://www.healthychildren.org/English/ages-stages/baby/Pages/Developmental-Milestones-7-Months.aspx
- Moon RY. "How to Keep Your Sleeping Baby Safe: AAP Policy Explained." HealthyChildren.org, 2026. https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/a-parents-guide-to-safe-sleep.aspx
- MedlinePlus. "Going home after a C-section." National Library of Medicine. https://medlineplus.gov/ency/patientinstructions/000624.htm
- Centers for Disease Control and Prevention. "Urgent Maternal Warning Signs and Symptoms." HEAR HER, 2024. https://www.cdc.gov/hearher/maternal-warning-signs/index.html