Portuguese versus Fenton Curve: Which one better explains maternal and neonatal outcomes in Portuguese women with gestational diabetes?

BACKGROUND AND AIMS: Growth charts are commonly used to identify foetal growth alterations, playing an important role as extreme growth centiles correlate with worse foetal and neonatal outcomes. This study aim was to compare birthweight classification (small for gestational age (SGA), adequate for gestational age and large for gestational age (LGA)) from women with gestational diabetes mellitus (GDM) by applying the population-based growth chart (Fenton Curve) and the standard chart customised for our country (Portuguese Curve). Moreover, we compared obstetric and neonatal outcomes according to birthweight classification between these curves. METHODS: A multicentre observational study with prospectively collected data from 19,470 pregnant women diagnosed with GDM (30 Portuguese institutions) was conducted. RESULTS: The proportion of SGA neonates was higher with Fenton Chart than with Portuguese standard chart (12.7% vs 10.9%) and the prevalence of LGA was higher using the Portuguese Chart (4.1%vs 10.9%). Statistically significant differences in the classifications given by the two curves and for maternal/neonatal outcomes were found. The Area Under the Curve and Akaike Information Criterion pointed out to a better correlation between weight classification of the Portuguese Curves and the majority of expected maternal and neonatal outcomes: gestational hypertension, preeclampsia, hydramnios, vaginal dystocic labour, hyperbilirubinemia, respiratory distress syndrome, trauma from delivery, admission in neonatal intensive care unit, prematurity and neonatal morbidity. CONCLUSION: Our study highlights the importance of having a standard birthweight curve specifically designed for each population. Neonates' weight classification carries prognostic implication and misclassification could lead to potential mistreatment or overtreatment.

HbA1c as a predictor of postpartum diabetes mellitus after gestational diabetes mellitus.

AIMS: Women diagnosed with Gestational Diabetes Mellitus (GDM) should be evaluated postpartum with an Oral Glucose Tolerance Test (OGTT). Nevertheless, women frequently fail to it. We intend to evaluate the performance of third trimester HbA1c in the prediction of postpartum diabetes mellitus (PDM). METHODS: We conducted a retrospective study of 10245 women with GDM based on the National Registry of GDM. A receiver-operating characteristic (ROC) curve was plotted to evaluate the diagnostic performance of third trimester HbA1c in PDM prediction. RESULTS: The mean third trimester HbA1c level was 5.81% (SD 0.69%) in women who developed PDM, 5.40% (SD 0.52%) in women with pre-diabetes and 5.21% (SD 0.43%) in women with normal glucose tolerance in postpartum OGTT, with statistically significant differences (p < 0.0001). As to the ROC curve ability to predict PDM was fair, with an optimal cut-off point of HbA1c of 5.4%. Women presenting HbA1c values ≥ 5.4% were 6.1 times more likely to develop PDM. CONCLUSIONS: A third trimester HbA1c level ≥5.4% is associated with a significant higher risk of PDM (p < 0.0001). It could be used as a reliable tool for screening women with GDM and detect who will benefit the most from a close follow-up after pregnancy.