Distinct modifiable risk factors and preventable burdens of preterm birth: a risk-stratified analysis of pregnancies with and without gestational diabetes mellitus.

BACKGROUND

Preterm birth (PTB) remains a major clinical and public health challenge worldwide. Gestational diabetes mellitus (GDM), complicating 14%-25% of pregnancies, elevates PTB risk via metabolic dysregulation. Although various early-pregnancy exposures are associated with PTB, their differential contributions in GDM-affected and unaffected pregnancies remain inadequately explored. This study aimed to identify distinct first-trimester modifiable risk factors for PTB in these two populations and to quantify the accurately preventable burden using an advanced estimation approach that accounts for interdependencies among risk factors.

METHODS

In this prospective cohort study conducted in Central China (2019-2024), 2,825 pregnant women were stratified into GDM (n = 554) and non-GDM (n = 2,271) groups. Assessed early-pregnancy exposures included advanced maternal age, smoking, depressive symptoms, physical inactivity, insufficient sleep, and pre-pregnancy overweight or obesity. Multivariable logistic regression and principal component analysis-adjusted population attributable fractions (PAFs) were employed to estimate the preventable PTB proportion, adjusting for overlap among risk factors.

RESULTS

Six modifiable risk factors were identified for GDM pregnancies, with a combined PAF of 73.7% and an adjusted combined PAF of 50.5%. For non-GDM pregnancies, four factors yielded a combined PAF of 44.2% and an adjusted combined PAF of 21.5%. Shared significant factors included smoking (PAF 27.4%, adjusted PAF 11.7% in GDM vs. PAF 22.7%, adjusted PAF 9.1% in non-GDM), depressive symptoms (22.7%, 11.6% vs. 15.0%, 6.0%), and overweight or obesity (18.1%, 7.7% vs. 11.9%, 4.8%). Risk factors specific to GDM pregnancies were advanced maternal age (11.6%, 4.9%), physical inactivity (19.3%, 8.2%), and insufficient sleep (14.9%, 6.4%). Low education was uniquely associated with PTB in non-GDM pregnancies (3.7%, 1.5%).

CONCLUSION

This study delineates distinct early-pregnancy modifiable risk profiles for PTB in GDM and non-GDM populations, supporting the development of targeted preventive strategies. Subsequent studies are warranted to validate these findings across diverse populations and to assess the effectiveness of tailored first-trimester interventions based on this risk stratification.