large for dates fetus

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Fetal macrosomia (also sometimes termed large for gestational age) is usually defined when the estimated fetal weight (EFW) is greater than the 90 percentile. According to this definition, it affects up to 10% of all live births. Some also use an increased birth weight (i.e. >4500g) in its definition.

Certain authors also use the 95 centile as the cut off and according to this definition, ~5% of fetuses would be affected .

Epidemiology

It typically presents in the 3 trimester. There may be some predilection for male fetuses.

Pathology

Associations

inaccurate dating
maternal obesity
increased maternal height
increased maternal age (>35 years)
maternal gestational diabetes
polyhydramnios
previous LGA baby
syndromes
placentomegaly

Radiographic features

Antenatal ultrasound

Often manifests with truncal obesity and therefore the abdominal circumference (AC) will be one of the first parameters to increase. The AC is also considered one of the best parameters .

According to some reports, an EFW of >4000 g within a week's window 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 .

Treatment and prognosis

Early delivery or elective Cesarian section are management options. Prognosis in a majority of cases is usually good.

Complications

Most complications are related to issues with delivery and include:

birth trauma, e.g. shoulder dystocia, brachial plexus injury
birth asphyxia
neonatal hypoglycemia (particularly in the setting of gestational diabetes)
meconium aspiration