Introduction Fetal macrosomia is increasing in prevalence and is associated with increased maternal and neonatal morbidity. Challenges include varying definitions, difficulties in accurate antenatal diagnosis and lack of consensus on ideal management in non-diabetic patients. We examined the management of large-for-gestational-age (LGA) pregnancies in our unit and compared obstetric outcomes of infants weighing 4250–4500 g and >4500 g respectively.
Methods We conducted a cross-sectional survey investigating detection and management of LGA pregnancies. We compared obstetric outcomes of 100 babies weighing >4500 g (mean weight 4720 g, SD 198.5) and 4250–4500 g (mean weight 4347 g, SD 75.3). Data was collected via retrospective case note review. Comparison was made between ultrasound estimated-fetal-weight (EFW) and actual birthweight.
Results The two groups were matched for maternal age, BMI and parity. There was no statistically significant difference between rate of LSCS, instrumental delivery or shoulder dystocia in the two groups (p=0.837,0.944). In the >4500 g group, 41% were LGA antenatally, 81% were managed expectantly and 77% delivered vaginally with a major complication rate of 2.6%. Ultrasound correctly predicted macrosomia in 6/16 cases (sensitivity 63%, specificity 40%) Abdominal circumference measurement alone and EFW estimation were equivalent in accuracy.
Conclusion Management of LGA pregnancy is often influenced by concerns about increased obstetric intervention and complication rates. However, we found no difference between vaginal delivery and shoulder dystocia rates in 4250–4500 g and >4500 g infants, supporting the available literature in advocating spontaneous vaginal delivery in LGA pregnancies. Comparison of EFW with actual birthweight highlights the poor sensitivity and specificity of ultrasound to correctly predict LGA pregnancy.