Fetal macrosomia, also sometimes termed large for gestational age (LGA),is usually defined when the estimated fetal weight (EFW) is greater than the 90th percentile. According to this definition, it affects up to 10% of all live births. Some also use an increased birth weight (i.e. >4500 g) in its definition.
Certain authors also use the 95th centile as the cut-off and according to this definition, ~5% of fetuses would be affected 8.
Often manifests with truncal obesity and therefore the abdominal circumference (AC) will be one of the first parameters to increase. The abdominal circumference is also considered one of the best parameters 8.
According to some reports, an EFW of >4000 g within a week from birth along with an increased amniotic fluid index (>20 cm) and relevant clinical factors are associated with fetal macrosomia at birth in ~70% of cases 3.
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Treatment and prognosis
Early delivery or elective cesarean section are management options. The prognosis in the majority of cases is usually good.
Complications
Most complications are related to issues with delivery and include:
1. Bjørstad AR, Irgens-hansen K, Daltveit AK et-al. Macrosomia: mode of delivery and pregnancy outcome. Acta Obstet Gynecol Scand. 2010;89 (5): 664-9. doi:10.3109/00016341003686099 - Pubmed citation
2. Thorsell M, Kaijser M, Almström H et-al. Large fetal size in early pregnancy associated with macrosomia. Ultrasound Obstet Gynecol. 2010;35 (4): 390-4. doi:10.1002/uog.7529 - Pubmed citation