On Growth Dynamics When the Time of Growth Is Unknown

• Activity Number: 684
• Type: Contributed
• Date/Time: Thursday, August 5, 2010 : 10:30 AM to 12:20 PM
• Sponsor: Section on Statistics in Epidemiology
• Author(s): Kai Fun Yu*+
• Companies: Eunice Kennedy Shriver National Institute of Child Health and Human Development
• Keywords: Growth dynamics ; fetal growth ; gestational age ; ultrasound measurements

Abstract

Ultrasound measurements such as fetal abdominal circumference, biparietal diameter and femur length are made at various times of the gestation. Such data arise from the Alabama Successive Small-for-Gestational Age Study conducted by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. When the initial measurement is made, the gestational age is at best estimated. There are different ways of estimating the gestational age such as the reported last menstrual period, those based on clinical examination of fundal height, date of fetal thickening, the date of fetal heart first heard with an unamplified fetoscope. One commonly used estimation method is by ultrasound measurement. The consequent use of ultrasound measurements to study fetal growth will be circular if the gestational age is estimated by ultrasound measurement. We shall therefore assume that the