Intrauterine Growth Curves at a High Altitude Area of Saudi Arabia

Background: Ideally, a population standard for intrauterine growth (IUG) ought to exist for each geographic region, and these standards should be well defined and documented allowing for comparisons. Objective: The aim of the present study was to construct intrauterine percentile growth charts for body weight, length and head circumference for local use in a high altitude area of Saudi Arabia. Methods: This is a crosssectional study of all Saudi births from Abha General Hospital over an eight year period (1997-2004). A total of 6035 Saudi births were included 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 to 42 weeks. The anthropometric measurements included birthweight, crown-heel length and head circumference. Tenth, 25th, 50th, 75th, and 90th percentiles for weight, length and head circumference were calculated against the periods of gestation. Mean weight, mean –2SD, and mean +2 SD were also calculated. The curves of best fit for weight, length and head circumference measurements at different weeks of gestation- were determined by polynomial regression of the following general form to construct the clinical curves ; Y=a + bX + cX 2 .Results: lUG curves for weight, length and head circumference were derived from measurements made on infants (n=6035) 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), distance (size attained) growth curves have been constructed. The median values for weight and length of infants of the present study are lower than those of published charts in all gestational periods. However, in case of head circumference, this was evident only before 32 weeks of gestation. At later gestations, the median values of head circumference were nearly comparable.Conclusion: These constructed smoothed gestational curves can be used as a useful tool for assessing the intrauterine growth of births born in high altitude areas of Saudi Arabia.