My baby girl just turned 6 months old (b
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My baby girl just turned 6 months old (born full-term at 39 weeks).
My in-laws came over this weekend and were alarmed because she cannot sit upright without immediately tipping over, and she has never rolled from her tummy onto her back yet. They insisted that 'all babies sit and roll by 6 months' and said she has a motor delay.
She does push up on her elbows during tummy time and reaches for toys.
We live in Columbus, Ohio (America/New_York). Can you evaluate her gross motor progress against the CDC 6-month milestone checklist (what 75%+ of babies do) and the WHO gross-motor achievement windows, tell us what to record, and give us one key observation to check tonight?
Answer
A full-term 6-month-old reads straight off the 6-month CDC card — at 39 weeks there's no age correction to apply.
Where she is on the 6-month movement items:
| 6-month item (CDC, 75%+) | Her |
| --- | --- |
| olls from tummy to back | Not yet |
| Pushes up with straight arms when on tummy | Elbows only |
| Leans on hands to support herself when sitting | Tips over |
Source: https://www.cdc.gov/act-early/milestones/6-months.html (accessed 2026-09-18)
Sitting without support has a WHO window of 3.8–9.2 months — that's the spread across healthy children, not a percentile for her and not a pass/fail line. She's at month 6, still well inside the window.
The in-laws' "all babies sit and roll by 6 months" doesn't match either the CDC 75% line (about 25% aren't there at 6 months) or the WHO window (up to 9.2 months for sitting). Missing two items on a checklist is not the same as a delay diagnosis — that distinction is what her doctor's screening is for.
Two rows to act on this week:
| Today | What to do |
| --- | --- |
| ecord | "6 months, full-term (39w); not yet rolling tummy-to-back; tips when sat upright; pushes on elbows and reaches for toys" — dated 2026-09-18 |
| Bring to her pediatrician | Ask for a formal developmental screening. AAP/CDC: at 9, 18, and 30 months, and any time a parent is concerned |
Source: https://www.cdc.gov/act-early/about/developmental-monitoring-and-screening.html (accessed 2026-09-18)
In parallel, Ohio's early-intervention program for under-3s is **Help Me Grow** — a parent can refer directly, no doctor order needed. Worth calling this week alongside the visit.
One check tonight, on the floor during tummy time: does she push up on straight arms with hands open and chest off the floor, or only on forearms? Straight arms is the 6-month item; elbows-only is the 4-month level. A clean yes/no tells you and her doctor where she is on this curve.
Has she rolled from her back onto her tummy yet?