There is a lack of consensus in the use of ultrasound for monitoring fetal growth among women with gestational diabetes (GDM) and pre-existing diabetes mellitus (DM). The poor accuracy of ultrasound for the prediction of fetal weight further limits its use for this purpose. In accordance with the Queensland Clinical Guidelines which recommends longitudinal growth assessment of fetus commencing 28-30 weeks, our unit performs at least one growth ultrasound for all women with diabetes in pregnancy. Further ultrasounds (2-4 weekly) are considered for women with poor blood glucose control or those who require pharmacological therapy.
This study aims to examine the use of ultrasound in women with GDM and pre-existing DM, and the birth weight of infants born to women in these groups.
A retrospective audit was conducted on women registered in the antenatal clinic from January to December 2015, with a diagnosis of GDM, pre-existing DM or maturity onset diabetes of the young (MODY). Data was collected from the diabetes register and electronic medical records.
Among 226 eligible women included in the study, there were 223 singleton and 3 twin pregnancies. Almost all (99.6%) women had at least one third trimester ultrasound. 60% of women with diet controlled GDM had one or less ultrasound while more than 60% of women requiring pharmacological therapy has at least two ultrasounds. 5.2% of infants had an estimated fetal weight (EFW) ≥90th centile while 12.2% had an estimated abdominal circumference ³90th centile. Only 4.8% of infants had an actual birth weight ≥4000g. 0.9% of infants had an EFW ≤10th centile and 4.8% had low birth weight of ≤2500g.
The data highlights the current use of ultrasound in a regional maternity unit for monitoring fetal growth among women with diabetes. Rates of macrosomia and low birth weight are lower than that reported in literature. Further research is required to assess the optimal frequency and timing of growth ultrasounds among women with diabetes, including the practicality of 2-4 weekly ultrasound in women requiring pharmacological therapy in a regional hospital.