The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) recommends that pregnant women have routine obstetric ultrasounds between 18 weeks and 22 weeks gestational age in order to confirm pregnancy timing, to measure the fetus so that growth abnormalities can be recognized quickly later in pregnancy, and to assess for congenital malformations and multiple gestations (i.e. Additionally, the ISUOG recommends that pregnant women have obstetric ultrasounds between 11 weeks and 13 weeks 6 days gestational age in countries with resources to perform them.