Rally 1B

Accuracy and Precision in Gestational Age Measurement: Physical Assessment Tools

Preterm birth is associated with many negative growth and development outcomes. With more accurate estimation of gestational age, we can better identify children who need intervention. In populations that have the most need, standard instruments used to estimate gestational age such as ultrasonography are generally not available. Furthermore, often the first time a child is measured is at birth, making gestational age estimation methods that rely on fetal measurements unusable. We need accurate gestational age estimation methods that rely only on measurements available at birth.


What combination(s) of physical assessments can accurately predict gestational age, especially in SGA and LGA children? Does that differ by geography?


Preterm birth (PTB) is defined by WHO as all births before 37 completed weeks of gestation or fewer than 259 days since the first day of a woman's last menstrual period (LMP). The gold standard is measurement of crown-rump length by ultrasound before 14 weeks gestation. We need gestational age measures during pregnancy (for management and surveillance) and after birth (on infant for cause of death, for surveillance and outcomes). The needed ppPrecision is ± two weeks (one week ideal) but greatest loss of sensitivity/specificity is between two and three weeks for surveillance and for clinical management impairment.


In this rally sprint the model was refined to improve prediction accuracy for SGA children. Model performance was also evaluated by geographic region. This provides additional insight into the working parameters of using physical measures to assess gestational age.