Susan Campbell Westerway 1, Rob Heard 2 and Jonathan Morris 1 University of Sydney, Department of Obstetrics & Gynaecology, Royal North Shore Hospital 1 School of Behavioural & Community Health Sciences 2 ASUM image planes for measuring the BPD, OFD, head circumference, abdominal circumference and long bones. Images are actual third trimester pregnancies reflecting the difficulty of perfect image planes. No statistically significant difference was seen for the BPD, OFD, HC & long bones between the study group & the general population based on the ASUM graphs. In 3/4 of the cases of macrosomic births to Caucasian women with GDM, both the head & abdominal circumference was greater than 1 standard deviation above the ASUM mean by 35 weeks gestation. There was no correlation between AC, HC and birth-weight. 8/9 babies of Chinese immigrant women (both with and without GDM) with AC > ASUM AC mean from 34 weeks had birth-weights > 3,600g. The Fisher exact probability that Chinese AC > ASUM mean from 34 weeks is unrelated to birth weight > 3600g was ASUM mean from 34 weeks predicts excess birth weight for Chinese. An increased AC prior to 34 weeks was non specific as 22% of Chinese had a raised AC which normalised after 34 weeks. Conclusion The mean birth weights of the groups in the study did not differ statistically from each other - Chinese (3312g) < Chinese GDM (3405g) < Caucasian (3435g) < Caucasian GDM (3486g). For Chinese fetuses an AC > ASUM mean beyond 34 weeks predicts birth weight above 3600g (p < ). This was not true for Caucasians. Ultrasound of the abdominal circumference after 34 weeks helped identify those fetuses of both Caucasian & Chinese women that were potentially larger than average and therefore at a greater risk of birth complications. Measurements prior to 34weeks gestation gave a high rate of false positives for predicting increased birth-weight. Literature 1. Hoffman L, Nolan C, Wilson J>D, Oats JN, Simmons D. Gestational diabetes mellitus – management guidelines.The Australasian Diabetes in Pregnancy Society. MJA 169;July Bochner CJ, Medearis AL, Williams J, Castro L, Hobel C. Early third trimester ultrasound screening in Gestational Diabetes to determine the risk of macrosomia & labour dystocia at term. Am J Obstet Gynecol 1987;157: Westerway SL, Keogh J, Heard R, Morris J. The incidence of fetal macrosomia & birth complications in Chinese immigrant women. Aust NZ J Obstet & Gynae 43;1: Buchanan TA, Kjos SI, Montoro MN, et al. The use of foetal ultrasound to select metabolic therapy for pregnancies complicated by mild gestational diabetes. Diabetes Care 1994;17:275. Acknowledgements Catriona Andronicos – Data Manager – OBSTET Data Base – NSAHS. Rosemary Hitchman and staff at Royal North Shore & Hornsby Ku-Ring-Gai Hospital Antenatal Clinics Results 3568 ultrasonic fetal measurements were performed. A one-way ANOVA showed no statistically significant difference in birth- weights between the groups. The abdominal circumference showed no statistically significant difference between the ASUM AC mean and Caucasian women with GDM. Fetuses of both Chinese GDM and normal Chinese women were below the ASUM AC mean but not statistically significantly different to the Queen Mary Abdominal Circumference. Appendix Three The Effect of Gestational Diabetes Mellitus on Fetal Size Northern Sydney Mean GDM GDM & Total Births with Health Statistics Birth-weight Macrosomia Macrosomia Caucasian Births g 2.3% 11.1% 15.3% Chinese Births g 12% 6.7% 10% THIS STUDY Mean Gestation/ Macrosomia NSH GDM & mean weight Macrosomia Caucasians 39w 4d 20% 11.1% With GDM 3486g Chinese 39w 1d 5% 6.7% With GDM 3405g Chinese 39w 3d 5% Non-GDM 3312g Weeks Queen Mary ASUM Gestation AC (mm) AC (mm) ___________________________________ mm 305 mm __________________________________ Introduction Gestational diabetes mellitus (GDM) is defined as glucose intolerance of any degree with onset or first recognition during pregnancy. 1 In Australia around 5% of Caucasian pregnancies are affected by GDM compared with 15% in Asians. 1 GDM may cause excessive fetal growth, particularly of the fetal abdomen 2, and an increased incidence of macrosomia (birth-weight > 4000g) and birth complications. Ultrasound is frequently required to assess fetal well being in pregnancies complicated by GDM. Chinese women have babies of lower birth-weight (Graph 1) and macrosomia in this group is considered to be a weight > 3,500g. 3 The fetal measurement charts used in Hong Kong and Beijing (The Queen Mary Charts) show no statistical difference to the ASUM charts for all fetal parameters except the abdominal circumference (Table 1), where a term baby is equivalent to 37 weeks on the ASUM AC chart. If these abdominal circumference differences are translated to our Chinese immigrant population then, when applied to a fetal weight formula, this may explain the difference in birth- weight between Caucasian and Chinese babies. Graph 1 Table 1. Methodology: Northern Sydney Health Study women were examined serially throughout the last 12 weeks of pregnancy. There were 3 groups: 25 Caucasian women with diet controlled GDM. 25 Chinese women with diet controlled GDM. Partners also Chinese. 25 Chinese without GDM. Partners also Chinese. Singleton pregnancy with known dates confirmed by ultrasound. Ultrasound at each Antenatal Clinic visit from 28 weeks gestation to measure BPD, OFD, head & abdominal circumference and long bones. Results plotted onto scatter graphs using Microsoft Excel. Statistical analysis performed with SPSS for Windows. Aims a. To determine if the mean fetal size in Caucasian & Chinese pregnancies affected by GDM varies from normal Caucasian or Chinese pregnancies. b. To determine if any ultrasonically measured fetal parameter helps predict excessive birth-weight of Chinese or Caucasian babies. Results Graph 4 – BPD Graph 5 - Head Circumference Graph 6 – Femur Length Graph 2 – Scatter Plot. Graph 3 – Mean Abdominal Circumference 229