Assessment of gestational age by new-born joint angles

Objective: We aimed to measure the joint angles of major joints in newborn babies to explore their association with gestational age (GA). Materials and Methods: This observational study was conducted to evaluate joint angles in healthy newborn infants, born between 28 and 41 completed weeks of gestation. Healthy and hemodynamically stable babies were selected by purposive sampling up to the 2nd day of life. Six major joints of upper and lower limbs (shoulder, elbow, wrist, hip, knee, and ankle) were assessed on either side. The joint angles and range of motion (ROM) achieved through predefined passive movements were measured by a single observer using a manual acrylic goniometer. The positioning of the joints during measurement was standardized. Results: A total of 433 newborn babies, belonging to different GA, were evaluated. The joint angles and ROM did not show any significant differences between right and left sides and between male and female babies. The ROM of flexion-extension and adduction-abduction movement at shoulder, angle of palmer-flexion at wrist, and angle of dorsiflexion at ankle, were observed to correlate strongly with GA (correlation coefficient r of –0.75, –0.74, –0.73, and –0.73, respectively). The relationships were inverse. A mathematical model based upon multiple regression analysis is proposed to predict GA from these four measurements. Conclusions: Structured clinical assessment of major joint angles in newborn babies has the potential to provide relatively precise estimation of GA, which may be used to add accuracy to modified New Ballard Score.