Rally 1A

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.


Improve the postnatal estimation of gestational age in order to determine preterm birth rates and small for gestational age rates with the goal of 90% to be ± 2 weeks across the gestational age spectrum to 28 weeks out to 42 weeks. Evaluate across sites and by sex.


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 precision 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.


The work in this rally demonstrated that the neurological portion of the physical assessments at birth are not necessary for accurate gestational age estimation. This allows for the reduction of tests that need to be done at birth and allows for increased standardization of those assessments.