What effect does injecting sugar into the amniotic fluid have on fetuses?

Injecting sugar into the amniotic fluid causes fetuses to swallow more. This phenomenon occurs because the presence of sweet-tasting substances in the amniotic fluid is detected by the developing fetus, prompting a stronger engagement in swallowing behaviors. The natural inclination of infants and fetuses to respond positively to sweet flavors is well-documented, and this response can be seen as an adaptive behavior, as swallowing is a critical function that prepares them for feeding after birth.

In experimental settings, when sugar is introduced into the amniotic fluid, studies have shown that fetuses increase their swallowing reflex, indicating their attraction to the taste. This behavior showcases the early development of gustatory preferences and highlights a basic instinct for survival that begins even before birth.