The Study
The association between interpregnancy intervals and preterm birth: a systematic review and meta-analysis
This study looked at lots of past records of moms and when they had babies, and found that moms who waited about 2 to 2.5 years between babies tended to have fewer premature babies. But it doesn't prove that waiting caused fewer premature babies—maybe other things like better healthcare or healthier lifestyles were also involved.
Analysis score
Maximum 85 for a systematic review with meta-analysis.
Where the score came from
This study looked at thousands of moms to find the best time to wait between having babies to avoid early births.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 545 / 100
Quality score
Systematic reviews and meta-analyses of cohort studies. They sit above a single cohort study but below a single randomized trial, because the underlying evidence is still observational.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — avoiding very short or very long gaps between pregnancies can help prevent babies from being born too early, which is safer for both mom and baby.
- 2Waiting 2 to 2.5 years between babies lowers the chance of early birth the most.
- 3Waiting less than 6 months makes early birth 64% more likely.
- 4Waiting over 5 years also slightly increases risk.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
BMC Pregnancy and Childbirth
Year
2025
Authors
Xueheng Wen, Weilun Liang, Jinguo Zhai, Yunxia Wang, Pingping Zheng, Shiying Wang
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Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.