Very low activity linked to earlier birth
In pregnancies with a short cervix, very low daily steps were tied to earlier delivery, while clinician-ordered activity restriction did not prolong pregnancy.
*Prospective cohort (ancillary study); Level 1b.
Citation
Sciscione AC, Booker WA, Clifton RG, et al. Activity Restriction in Pregnancy and the Risk of Early Delivery: The AWARE Study. Obstetrics & Gynecology. 2026;147(4):451–459. doi:10.1097/AOG.0000000000006225.
Background
Activity restriction is often recommended to prevent early birth, despite limited evidence and known harms. This study measured real-world activity with a wrist device in people at high risk for early delivery due to a short cervix.
Patients
Pregnant people 16–23 weeks with a short cervix on ultrasound (singletons and twins) enrolled in two prevention trials; those who never wore the device were excluded.
Intervention
Lower activity (main comparison: median <3,500 steps/day; secondary: <5,000 steps/day).
Control
Higher activity (≥3,500 steps/day; ≥5,000 steps/day).
Outcome
Primary: time from enrollment to delivery. Secondary: gestational age at delivery, early birth before 34 weeks, and selected newborn outcomes.
Follow-up Period
From enrollment until delivery.
Results
The primary outcome (time from enrollment to delivery) did not differ by activity level.
| Comparison |
Significant outcome |
Effect size |
Absolute difference (approx.) |
| <3,500 vs ≥3,500 steps/day |
Early birth before 34 weeks (secondary) |
Adjusted relative risk 2.30 (95% CI 1.08–4.90) |
29.6% fewer events with ≥3,500 (NNT≈4) |
| <3,500 vs ≥3,500 steps/day |
Gestational age at delivery (secondary) |
Adjusted median difference −1.9 weeks (95% CI −3.7 to −0.1) |
About 2 weeks earlier with <3,500 |
| <5,000 vs ≥5,000 steps/day |
Newborn intensive care unit admission (secondary) |
Adjusted relative risk 1.61 (95% CI 1.03–2.50) |
13.4% fewer admissions with ≥5,000 (NNT≈8) |
Limitations
Small sample and activity level was not randomized, so low steps may reflect other problems that also raise early-birth risk. The device could not confirm wear time versus true inactivity. Findings apply to a higher-risk “short cervix” population.
Funding
U.S. National Institute of Child Health and Human Development grants.
Clinical Application
Do not prescribe routine activity restriction for short cervix. Encourage normal daily activity when safe; very low activity may flag patients needing closer monitoring.