Association between gestational diabetes mellitus and adverse pregnancy outcomes and effect modification by maternal age in a population based cohort study

Gestational diabetes mellitus (GDM) is a rising public health issue and comes with many negative pregnancy effects for both mothers and infants. Because there is an increasing pattern in advanced maternal age around the globe, it has become very important to know whether age changes the effect of GDM on pregnancy outcomes. This study aimed to look at the links between GDM and major maternal and neonatal complications in a large population-based cohort and see if maternal age modifies this relationship. This population-based cohort study was carried out using Sina electronic health records and what we found was after carefully applying the inclusion and exclusion criteria we had set, a total of 424,359 pregnant women made the cut. A diagnosis of GDM was made according to the strict criteria laid out by the International Association of Diabetes and Pregnancy Study Groups (also known as the IADPSG ones) The study focused on various negative outcomes including Caesarean sections, premature births, low birth weights, babies being over-sized for their gestational age, admissions to the neonatal ICU and a range of hypertensive disorders. We plumped for logistic regression models to work out adjusted odds ratios (the fancy bit is that we tried to remove other possible factors that could have had an influence on the results) and 95% confidence intervals to see how reliable our findings were. To see whether the presence of GDM interacted with age of the mother we looked at two age groups < 35 years and ≥ 35 years. We did this by including a multiplicative interaction term in our analysis. Among the total cohort, 19,861 women (4.7%) had GDM.After full adjustment for sociodemographic, behavioral and clinical factors, GDM was associated with significantly higher odds of cesarean delivery (aOR 1.79, 95% CI 1.73−1.84; P < 0.001), preterm birth (aOR 1.76, 95% CI 1.66−1.86; P < 0.001), LBW (aOR 1.15, 95% CI 1.08−1.22; P < 0.001), macrosomia (aOR 1.75, 95% CI 1.66−1.85; P < 0.001), NICU admission (aOR 1.38, 95% CI 1.32−1.44; P < 0.001) and HDP (aOR 2.44, 95% CI 2.29−2.60; P < 0.001). In age stratified analyses, GDM remained associated with all adverse outcomes in both groups. A statistically significant interaction with maternal age was observed only for macrosomia (p-value for interaction term = 0.007), with a stronger association among women < 35 years (aOR 1.82, 95% CI 1.68−1.98) than among women ≥ 35 years (aOR 1.63, 95% CI 1.51–1.75). GDM was associated with higher risks of serious health problems for mothers and newborns in this large study. Younger mothers were more likely to have heavier babies as a result of GDM, but most associations were not modified by the mothers age. The study shows that GDM affects women of all ages. But it also indicates that fetal overgrowth has a tendency to occur in younger women with GDM.