Birth anthropometric parameters in high and low altitude areas of Southwest Saudi Arabia

OBJECTIVE: To study the anthropometric parameters of Southwestern Saudi newborns in Abha (a high altitude area) and Baish (a sea level area of Southwestern Saudi Arabia); to compare these parameters with those of the United States Center for Disease Control 2000 growth charts and to estimate the incidence of low birth weight (LBW) among the study population.

METHODS: The study sample included all births from Abha Central Hospital (N=4300), and all births from Baish General Hospital (N=1200), Kingdom of Saudi Arabi during the period from January 2001 to January 2003. Only term births (>37-42 weeks gestation) were included. The anthropometric measurements included birthweight, crown-heel length and head circumference. The head circumference (occipitofrontal) was measured to the nearest 5 mm with an inelastic tape. Babies of LBW were identified. Low birth weight was defined as <2,500 gms at birth. Ponderal index (PI) was calculated using the formula of birthweight (in grams) x 100/length3.

RESULTS: Saudi newborns are lighter and shorter than those of National Center for Health Statistics newborns. The same finding was evident for head circumference. Newborns from Abha are lighter(p<0.001) and shorter (p<0.001) than from Baish. However, this difference was not significant for head circumference (p=0.53). Abha newborns showed significantly lower mean weight (2845.4 gms versus 2951.8 gms, t=58, p<0.001), and lower mean length (48.1 cm versus 48.5 cm, t=4.65, p<0.001). Low birth weight was prevalent among 24.6% of all newborns. This figure was significantly higher among newborns from Abha (25.7%) than its counterpart in Baish (20.7%), p<0.001. A strong positive correlation between the PI and birthweight (p<0.0001, R2=0.52), after adjusting for the place of birth was evident.

CONCLUSION: Neonates of Southwestern Saudi Arabia are significantly lighter and shorter than those of the reference population, as well as neonates in other areas of the Kingdom, with prevalent LBW especially in high altitude area, possibly due to intra-uterine growth retardation of secondary type. Ponderal index is significantly associated with birth weight even after adjusting for gender and place of birth. This might encourage the use of PI as an alternative to birth weight especially when gestational age is not available.