AIM: To assessed hyperglycaemia in pregnancy (HIP) prevalence trends over the past decade, accounting for risk factors and screening practices (France introduced early risk-based HIP screening in 2010). METHODS: We analysed national delivery data from the French National Health Data System (SNDS) (2012-2022), excluding women with pre-existing diabetes (n=8,172,911). Poisson regressions with generalized estimating equations estimated prevalence ratios (PR) for HIP risk factors. Counterfactual scenarios quantified contributions of maternal age, early screening, and pre-pregnancy overweight to HIP increase. RESULTS: HIP prevalence increased from 7.5% in 2012 to 15.7% in 2022, with early HIP tripling. Prevalence rose in 2020-2021 during the Covid-19 pandemic. After adjustment for maternal age, parity, socioeconomic status, season of pregnancy onset, place of delivery, regional prevalence of pre-pregnancy overweight, and early screening, the aPR were 1.30 [1.11-1.51] in 2021 and 1.15 [0.97-1.36] in 2022 vs. 2012 (unadjusted: 2.24 [2.22-2.26] and 2.08 [2.06-2.10]), suggesting that these factors account for a large proportion of the observed increase. While the observed increase in HIP prevalence was 8.2 percentage points from 2012 to 2022, counterfactual scenarios estimated increases of 6.5 [5.9-7.3] for constant maternal age, 6.2 [5.1-7.7] for constant early screening (13.7%), and 4.3 [2.4-5.9] for constant regional pre-pregnancy overweight (11.8%) at 2012 levels. CONCLUSION: Rising maternal age, increased early HIP screening, and higher regional pre-pregnancy overweight prevalence mostly contributed to HIP prevalence increase. Public health strategies should prioritize modifiable risk factors-particularly pre-pregnancy overweight-and evaluate the effectiveness of early screening practices.