Pregnancy fasting was associated with slightly lower average birthweight
Observational evidence found a small birthweight difference and an inconclusive low-birthweight association, leaving broader pregnancy safety questions unanswered.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
Fasting during pregnancy was associated with slightly lower average birthweight. The pooled low-birthweight analysis did not show a statistically clear association. Because all included studies were observational, these results cannot establish that fasting caused the weight difference or that fasting is safe across pregnancy stages, maternal conditions, or longer-term child outcomes.
Only a subset of included studies contributed quantitative data, and birthweight estimates varied across studies. The abstract does not describe fasting schedules or reference groups in enough detail to assess comparability.
What the abstract measured
Researchers examined average newborn weight separately from low birthweight, defined as below 2500 g. A small shift in average weight does not necessarily imply a detectable change in the proportion below that threshold.
What certainty ratings cannot settle
The authors rated evidence certainty differently for average birthweight and low birthweight. Those ratings do not remove the limits of observational data, and the abstract leaves trimester-specific effects and later developmental outcomes unresolved.
The original publication
Intermittent Fasting During Pregnancy and Neonatal Birth Weight: A Systematic Review and Meta-Analysis.
Giorno A, De Simone C, Lopez G et al.
Nutrients · 2025
- PubMed ID
- 41305597
- Record checked
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