Amniotic fluid composition responds to changes in maternal dietary carbohydrate and is related to metabolic status in term fetal rats.

The objective of this study was twofold: 1) to determine whether amniotic fluid composition responded to differences in the level or source (glucose vs. fructose) of maternal dietary carbohydrate, and 2) to establish whether any dietary-induced changes in amniotic fluid composition correlated with maternal or fetal metabolic status at term. Pregnant rat dams were fed graded levels (0, 4, 12 and 60%) of glucose or fructose in a triglyceride-based diet (Experiment 1) or isoenergetic low carbohydrate diets having 4% glucose equivalents as glucose, fructose, or lipid-glycerol (Experiment 2) throughout pregnancy. Amniotic fluid and maternal and fetal samples were collected at term (d21). Results demonstrated a significant increase in amniotic fluid glucose and a significant decrease in amniotic fluid uric acid as the level of carbohydrate increased in the maternal diet. Pearson correlation coefficients showed amniotic fluid glucose to be positively associated with maternal and fetal liver glycogen and fetal weight; amniotic fluid uric acid and urea nitrogen were negatively correlated with these same measures. Regression analysis indicated that amniotic fluid glucose was predictive of fetal body weight and fetal liver glycogen at term. The findings show that amniotic fluid can be modified by maternal diet and suggest that composition of amniotic fluid might be used as an accessible nutritional indicator of carbohydrate status in the developing fetus.