Final answer:
Abdominal distention at birth can indicate the passage of meconium, which is a sign of fetal distress and hypoxia. This can be caused by various factors and is more common in full-term or post-term newborns.
Step-by-step explanation:
Abdominal distention at birth can indicate the passage of meconium, which is a sign of fetal distress, particularly fetal hypoxia (oxygen deprivation). This can be caused by various factors such as maternal drug abuse, maternal hypertension, depletion of amniotic fluid, long labor or difficult birth, or a defect in the placenta. Meconium passage is more common in full-term or post-term newborns. Fetal distress can stimulate the vagus nerve, triggering gastrointestinal peristalsis and relaxation of the sphincter, leading to the passage of meconium.