The effects of pre-pregnancy body mass index and rate of weight gain during the second trimester on maternal lipid profiles, adiponectin, insulin resistance and omega-3/OMEGA-6 fatty acids

Pregnancy is a process that occurs physiological, hormonal and metabolic changes in the female body. The change in fat metabolism during pregnancy has significant effects on many systems, especially on neuronal development of the fetus. Insulin sensitivity increases during early gestation leading to an increase in maternal fat deposits. In later pregnancy stage, depending on the physiological insulin resistance fat deposits are destroyed as a result of lipolysis. It is postulated that in overweight and obese pregnant women, the effects on lipid metabolism are more prominent especially if the rate of weight gain in 2nd trimester is higher. This study investigates the relationship between pregestational body mass ındex (pBMI) and the rate of gestational weight gain (GWG) at the 2nd trimester with the biomarkers of lipid, fatty acids metabolism and insulin resistance. Sixty nine pregnant women followed at DEU Hospital Gynecology and Obstetrics Department between June 2016-November 2017 were included in this study. The body weights of the pregnant women were measured at 11-14th and 24-28th weeks of pregnancy and blood samples were obtained. Rate of GWG (kg/week) was determined. The pregnant women were stratified according to their pBMI and the rate of GWG at the 2nd trimester. Glucose, total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol, insulin levels were measured by routine biochemical methods, HOMA-IR was calculated. Adiponectin levels were measured by ELISA method and fatty acids were measured by GC-MS. For the statistical analysis, paired t test, independent t test, Mann Whitney U and Wilcoxon test were used on SPSS 23 program. Pregestational BMI was <25 for 38 women and ≥25 for 31 women. The second trimester rate of GWG was normal in 22 women and high in 47 women. The rate of GWG was significantly higher for the group with pBMI<25 (0,52±0,14), compared to the group with pBMI≥25 (0,43±0,18) (p=0,024). Triglyceride, total cholesterol, HDL cholesterol, LDL cholesterol, insulin, HOMA-IR, myristic acid, palmitic acid, gamma linolenic acid, linoleic acid, oleic acid, arachidonic acid, DHA, total n-6 fatty acids, total n-3 fatty acids, n-6 / n-3 levels increased significantly in the 2nd trimester compared to the first trimester for the whole group. When the group with BMI≥25 was compared to the group with BMI<25; insulin and HOMA-IR levels were found to be significantly higher (p<0.01) at both trimesters. The levels of oleic acid in the first trimester; palmitoleic acid, oleic acid, stearic acid, arachidonic acid in the second trimester were significantly higher in the group with higher pBMI. When the group with high GWG was compared to the group with normal GWG; there was no significant difference between the values of any biochemical parameters at neither the first nor the second trimester. The changes in lipid parameters, free fatty acids, insulin and HOMA-IR at the 2nd trimester were compatible with the changes in lipid metabolism and the development of insulin resistance. The fact that pregnant women with higher pBMI has siginificantly higher levels of insulin and HOMA-IR at both trimesters shows that for these women the development of insulin resistance is more prominent. On the other hand, rate of GWG was not significantly effective on metabolic markers. As a result; The pregestational BMI can be considered as a more important predictor of adverse metabolic outcomes compared to the rate of GWG.