RESUMEN
In this article we seek to determine the effect of the knowledge of prenatal fetal sex, through the use of ultrasound, on infant mean birth weight and the proportion of low birth weight (LBW) babies. A sample population of 1,195 women (cases, n = 640; control, n = 555) were studied in relation to their knowledge of the sex of the fetus in three hospitals in Amman, Jordan. It was found that prenatally known males had the highest mean birth weights (MBWs) as compared with females. It is proposed that these differences could be attributed to behavioral factors related to son preference. The authors conclude that further research on the actual link between prenatal detection of fetal sex and health behavior as indicated by birth weight is needed.