Endocrine Abstracts

Background: It is estimated that gestational diabetes (GDM) accounts for 87.5% of all diabetes cases in pregnancy and is associated with worse pregnancy outcomes. Macrosomia is one of the main complications of GDM and antenatal management strategies are directed at ensuring normal foetal growth. Ultrasonography is a useful tool for estimating foetal size, but there is little data in the literature correlating foetal abdominal circumference (AC) and birth weight in GDM. Furthermore, the use of HbA1c as a marker of glycaemic control (and hence pregnancy outcomes) in GDM is controversial. We therefore aimed to correlate AC measured at 36 weeks gestation and glycaemic control as measured by mean pregnancy HbA1c with foetal birth weight at delivery.

Methods: We performed a retrospective analysis of the biochemical results and ultrasound measurements of 496 women with singleton pregnancies who had had GDM diagnosed by OGTT at 26–28 weeks of gestation between 2008 and 2013. A statistical analysis was performed using the SPSS statistical package.

Results: The mean AC was 320±24 mm (mean±S.D.) and the mean foetal birth weight was 3208±500 g (mean±S.D.). There was a moderate positive correlation between AC and foetal birth weight (Pearson correlation coefficient 0.625; P<0.001). There was no statistically significant correlation between AC or foetal body weight and the HbA1c test performed in the first/second and third month following OGTT (all P>0.10).

Conclusions: Foetal ultrasound growth scan with measurement of the abdominal circumference is a useful tool in predicting foetal birth weight with positive correlation between foetal AC and birth weight endorsing current clinical practice. Although HbA1c is an established gold standard for assessing glycaemic control it provides little benefit in predicting macrosomia in the setting of GDM.