Charts of Thai fetal biometry: Upper extremities.

ABSTRACT

A cross-sectional study was conducted in order to construct a reference chart for Thai fetal upper extremities long bone (humerus, radius, and ulna). A total of 621 normal pregnant women, who attended the antenatal clinic at Siriraj Hospital, Mahidol University, Bangkok, were recruited between 12 and 41 weeks of gestation. We identified pregnant women who had previous regular menstrual period for at least 3 months without contraception prior to current pregnancy; and uterine size at the time of examination was compatible with menstrual age. Each fetus was measured only once at a randomly assigned gestational age specifically for the purpose of this study. Due to unfavorable fetal position in some cases, data were available in only 482 measurements of the humerus, and 443 measurements of the radius and ulna respectively. Linear regression models were fitted separately to estimate the mean and standard deviation at each gestational age for each parameter. New reference centiles were constructed from both equations, assuming the data were normally distributed. This will provide more reliable reference data to be utilized in the assessment of gestational age and in the diagnosis of upper limb deformities during fetal period.