Association between high maternal haemoglobin levels in the first trimester and gestational diabetes mellitus: a prospective birth cohort study.
Recent studies suggest first-trimester maternal haemoglobin (Hb) may be linked to gestational diabetes mellitus (GDM), but evidence remains limited. This study examined the association between high first-trimester haemoglobin and GDM risk.
This prospective study included 18 484 singleton pregnant women with a gestational age of ≤14 weeks in the Fujian Birth Cohort Study. Haemoglobin of the first trimester is divided into low (<110 g/L), normal (110-130 g/L) and high (≥130 g/L). Multivariate logistic regression and restricted cubic spline (RCS) models were used to explore the association between Hb level and GDM risk, and to gradually adjust sociodemographics, lifestyle and metabolic factors. Stratified and combined analysis was performed according to maternal age, pre-pregnancy body mass index and mode of conception.
Mean early Hb was 127.3 ± 9.6 g/L. The crude GDM incidence was 17.7%, 19.6%, and 25.3% in the low, normal, and high Hb groups, respectively. High Hb was significantly associated with increased GDM risk in crude (odds ratio (OR) = 1.40; 95% confidence interval (CI) = 1.30-1.50, P < 0.001), Model 2 (OR = 1.31; 95% CI = 1.22-1.41, P < 0.001), and Model 3 (OR = 1.24; 95% CI = 1.15-1.34, P < 0.001), with only 5.3% attenuation after adjusting for metabolic markers. Restricted cubic spline analyses showed a linear positive dose-response relationship between Hb and GDM risk (P for nonlinearity = 0.274). The association was stronger in non-advanced maternal age (non-AMA), overweight/obese, and spontaneously conceiving women, and combined effects were observed for high Hb with AMA, overweight/obesity, and assisted reproductive technology (ART).
Early pregnancy haemoglobin is significantly associated with GDM risk, modified by age, pre-pregnancy BMI, and conception mode. Haemoglobin screening in early pregnancy may help identify high-risk women. Further studies are needed to clarify related mechanisms and evaluate interventions.
This prospective study included 18 484 singleton pregnant women with a gestational age of ≤14 weeks in the Fujian Birth Cohort Study. Haemoglobin of the first trimester is divided into low (<110 g/L), normal (110-130 g/L) and high (≥130 g/L). Multivariate logistic regression and restricted cubic spline (RCS) models were used to explore the association between Hb level and GDM risk, and to gradually adjust sociodemographics, lifestyle and metabolic factors. Stratified and combined analysis was performed according to maternal age, pre-pregnancy body mass index and mode of conception.
Mean early Hb was 127.3 ± 9.6 g/L. The crude GDM incidence was 17.7%, 19.6%, and 25.3% in the low, normal, and high Hb groups, respectively. High Hb was significantly associated with increased GDM risk in crude (odds ratio (OR) = 1.40; 95% confidence interval (CI) = 1.30-1.50, P < 0.001), Model 2 (OR = 1.31; 95% CI = 1.22-1.41, P < 0.001), and Model 3 (OR = 1.24; 95% CI = 1.15-1.34, P < 0.001), with only 5.3% attenuation after adjusting for metabolic markers. Restricted cubic spline analyses showed a linear positive dose-response relationship between Hb and GDM risk (P for nonlinearity = 0.274). The association was stronger in non-advanced maternal age (non-AMA), overweight/obese, and spontaneously conceiving women, and combined effects were observed for high Hb with AMA, overweight/obesity, and assisted reproductive technology (ART).
Early pregnancy haemoglobin is significantly associated with GDM risk, modified by age, pre-pregnancy BMI, and conception mode. Haemoglobin screening in early pregnancy may help identify high-risk women. Further studies are needed to clarify related mechanisms and evaluate interventions.