Timing	Parameters
11–14 weeks of gestation	Early scan is performed to: confirm gestational age using crown-rump length measurement assess for major structural malformations, including acrania and anencephaly
18–20 weeks of gestation	Detailed structural anatomy scan which includes the spine and heart is performed (four-chamber, outflow tract and three-vessel views)
28–36 weeks of gestation	Serial growth scan is performed every four weeks to assess fetal growth and amniotic fluid volume The rate of fetal growth should be used to facilitate decisions involving treatment as well as timing and mode of delivery