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Life sciences · Journal article
Journal of Obstetrics and Gynaecology · July 19, 2026
Well-designed and adequately powered for the question it asks.
This large Chinese cohort of 2832 twin pregnancies demonstrates that both inadequate and excessive gestational weight gain, measured by z-scores, independently increase preterm birth risk. The findings provide population-specific weight gain targets narrower than existing IOM recommendations, with z-scores between the 25th-75th percentiles associated with lower preterm birth rates.
Hospital-based retrospective design limits causal inference. Chinese women with twin pregnancies between January 1, 2015, and December 31, 2019.
Low z-scores (<P25) associated with increased spontaneous PTB risk (adjusted OR 1.35, 95% CI 1.05-1.74) High z-scores (≥P75) associated with increased spontaneous PTB risk (adjusted OR 1.28, 95% CI 0.99-1.66) Low z-scores associated with iatrogenic PTB (adjusted OR 1.40, 95% CI 1.12-1.76) and high z-scores with iatrogenic PTB (adjusted OR 1.97, 95% CI 1.57-2.47)
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Clinicians managing twin pregnancies in Chinese populations should counsel patients toward weight gain targets between the 25th-75th percentile z-scores, which are narrower than IOM guidelines. Both inadequate and excessive weight gain significantly increase preterm birth risk, with the highest risk for iatrogenic preterm birth in those with excessive gain (OR 1.97).
Large retrospective cohort of 2832 twin pregnancies demonstrates significant dose-response associations between weight gain z-scores and preterm birth with adjusted odds ratios and confidence intervals.
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Quoted from the source exactly as published.
Clinicians managing twin pregnancies in Chinese populations should counsel patients toward weight gain targets between the 25th-75th percentile z-scores, which are narrower than IOM guidelines. Both inadequate and excessive weight gain significantly increase preterm birth risk, with the highest risk for iatrogenic preterm birth in those with excessive gain (OR 1.97).
Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.
Background. To evaluate the association between the weight-gain-for-gestational-age z-score and preterm birth (PTB) in a large Chinese twin pregnancy cohort.Methods. A hospital-based retrospective study included 2832 twin pregnancies between January 1, 2015, and December 31, 2019. The primary composite outcome was defined as PTB. The total gestational weight gain was converted into z-score, and logistic regression models were used to examine the associations between z-scores and PTB.Results. We developed a weight-gain-for-gestational-age z-score to determine the gestational weight gain during twin pregnancies in Chinese women. Low (<P25) and high (≥P75) z-scores were associated with a higher risk for spontaneous PTB (SPTB) than scores between the 25th and 75th percentiles (adjusted odds ratio [OR]: 1.35, 95% confidence interval [CI]: 1.05-1.74; 1.28, 0.99-1.66; respectively). Similarly, low z-scores (1.40, 1.12-1.76) and high z-scores (1.97, 1.57-2.47) were also associated with an increased risk for iatrogenic PTB (IPTB). Normal weight subgroups exhibited comparable outcomes. In addition, z-scores between the 25th and 75th percentiles indicated an equivalent total gestational weight gain at 37 weeks of 15.8-20.9 kg for underweight, 14.6-20.3 kg for normal weight, and 11.8-18.6 kg for overweight or obese women, which are narrower than the 2009 IOM recommendation.Conclusions. Our findings indicate that inadequate gestational weight gain, as evaluated by the z-score, is associated with a significantly increased risk for SPTB, whereas inadequate and excessive gestational weight gain are associated with a significantly increased risk for IPTB, in a large Chinese twin pregnancy cohort.
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