Approximately 8% of pregnancies in the United States are affected by gestational diabetes mellitus (GDM) per year. The condition is associated with higher risk of adverse perinatal outcomes, including hypertensive disorders of pregnancy, cesarean delivery (CD), macrosomia, shoulder dystocia, neonatal hypoglycemia, and adverse long-term outcomes, including diabetes and cardiovascular disease. Randomized clinical trials have suggested that glycemic control of GDM with medical nutritional and insulin therapies may improve perinatal outcomes. The American Diabetes Association recommends using self-monitoring of blood glucose (BG) to manage glycemic control during pregnancy. However, large-scale, population-based studies evaluating self-monitoring of BG are limited. In addition, the conventional model for glycemic control status using optimal versus suboptimal is insufficient to capture progressive changes during pregnancy. The aim of this study was to review whether glycemic control trajectories (GCTs) from GDM diagnosis to delivery are associated with the risk of perinatal complications.
This was a population-based, cohort study of individuals with GDM who received prenatal care in an integrated health care delivery system between 2007 and 2017. Included were those diagnosed with GDM at 24 to 28 weeks of gestation. Excluded were those who had diabetes before pregnancy. Individuals were asked to self-monitor BG measurements to assess glycemic control 4 times per day at mealtimes. The measurements were collected by nurses or dietitians during weekly counseling calls. Optimal glycemic control was defined as <95 mg/dL for fasting and <140 mg/dL for 1 hour after lunch or dinner. Perinatal complications were the outcomes measured, including CD, preterm birth, shoulder dystocia, neonatal intensive care unit (NICU) admission, NICU stays ≥7 days, stillbirth, large-for-gestational age (LGA), and small-for-gestational age (SGA). To estimate associations between GCTs with the perinatal complications, multivariate Poisson regression models were used.
A total of 26,774 individuals were included in the analysis. Four distinct GCTs were identified: trajectory 1 (T1) for stably optimal GCTs (39.3% of individuals), trajectory 2 (T2) for rapidly improving GCTs (34.9%), trajectory 3 (T3) for slowly improving to near-optimal GCTs (15.4%), and trajectory 4 (T4) for slowly improving to suboptimal GCTs (11%).
For the T1 group, there were lower risks of CD (adjusted relative risk [aRR], 0.93; 95% confidence internal [CI], 0.89–0.96), shoulder dystocia (aRR, 0.75; 95% CI, 0.61–0.92), and NICU admission (aRR, 0.90; 95% CI, 0.83–0.97) compared with the T2 or reference group (P for trend <0.001), whereas for the T4 group there were higher risks of CD (aRR, 1.18; 95% CI, 1.12–1.24; P for trend <0.001), shoulder dystocia (aRR, 1.41; 95% CI, 1.12–1.78; P for trend <0.001), and NICU admission (aRR, 1.33; 95% CI, 1.20–1.47; P for trend <0.001). There was an increased risk of LGA across GCTs (from T1 [aRR, 0.74; 95% CI, 0.69–0.80] to T4 [aRR, 1.42; 95% CI, 1.31–1.53]; P for trend <0.001; vs T2), but there was a decreased trend of SGA (from T1 [aRR, 1.10; 95% CI, 1.02–1.20] to T4 [aRR, 0.63; 95% CI, 0.53–0.75]; P for trend <0.001). There was not a significant trend across GCTs for the risk of preterm birth and NICU stays ≥7 days.
Overall, there was increasing risk of perinatal complications from T1 to T4 GCT, except for SGA. This study highlights the need for early GDM management to prevent perinatal complications.