Construction of intrauterine growth curves in a high altitude area of Saudi Arabia

OBJECTIVE: The aim of the present study was to construct intrauterine percentile growth curves for body weight, length and head circumference for local use in a high altitude area of Saudi Arabia.

METHODS: This is a cross-sectional study of all Saudi births from Abha General Hospital over a 6-year period from 1999 to 2004. We included a total of 6,035 Saudi births in the present study after eliminating babies that were stillbirths, twins or those with major congenital anomalies. The gestational age of the infants ranged from 26-42 weeks. The anthropometric measurements included birth weight, crown-heel length and head circumference. We calculated the 10th, 25th, 50th, 75th, and 90th percentiles for weight, length and head circumference against the periods of gestation. We also calculated the mean weight and mean ± 2SD. We determined the curves of best fit for weight, length and head circumference measurements at different weeks of gestation by polynomial regression of the following general form to construct the clinical curves: Y = a + bX + cX2.

RESULTS: We derived intrauterine growth curves for weight, length and head circumference from measurements made on infants born at each week of gestation in the latter half of pregnancy. By calculating mean values and deviations around these (expressed either as centiles or standard deviations), we constructed distance (size attained) growth curves. The mean values for weight and length of births of the present study are lower than those of published charts in all gestational periods. However, for head circumference, evident appeared only before 32 weeks of gestation. The mean values of head circumference were nearly comparable.

CONCLUSION: Constructed smoothed gestational curves are a useful tool for assessing the intrauterine growth of births in high altitude areas of Saudi Arabia.