Maternal lipid metabolism changes apparently throughout gestation. During the 1st two-thirds of gestation, there is an elevation in fat accumulation, related to hyperphagia and increased lipogenesis [10, 11]. In the last 3rd trimester of gestation, maternal fat storage decreases due to the enhanced lipolytic activity and declined lipoprotein lipase activity [12, 13]. These alterations are reflections of maternal physiologic adaptation to energy demand of the fetus, as well as preparations for delivery and lactation . Gestational dyslipidemia, an abnormal elevation of lipids, has been associated with adverse pregnancy complications, including GDM and HDP. Although most studies show that circulating lipid patterns are different between GDM and normal pregnancy, results have been inconsistent . It has been reported that patients with GDM have increased concentrations of TG, TC and LDL-C and lower levels of HDL-C [16, 17]. However, other studies indicate that no elevated serum TC and LDL-C levels were found in the 1st, 2nd, and 3rd trimesters, between patients with GDM and normal pregnant women . Furthermore, there is no changes of TG levels in GDM group compared to non-diabetic group . The TG/HDL-C ratio is higher in GDM compared with normal pregnancy [20, 21]. In present study, we found that women with GDM had higher levels of TG, AIP and lower levels of TC and HDL-C than that of control. We further revealed that the incidence of GDM was positively correlated with levels of TG and AIP, while negative correlated with HDL-C. Thus, our data suggested abnormal maternal lipids have a role in the pathogenesis of GDM.
HDP can be classified by the terms chronic hypertension, gestational hypertension (GH), preeclampsia (PE) or chronic hypertension with superimposed PE . Evidence suggests that HDP is closely related to lipid profile abnormalities, however, data still are conflicting. Contini et al reported that high concentrations of TG are a feature of PE . A meta-analysis demonstrates that patients with PE have increased levels of TG and TC through pregnancy, as well as lower levels of HDL-C in the third trimester . Other studies do not found any differences of neither TG nor TC levels between PE and uncomplicated pregnancies . Our results illustrated that compared with the control group, the HDP group showed higher TG concentrations and AIP in the second trimester. Furthermore, AIP was correlated positively with the incidence of HDP. Collectively, these data suggested that lipids in women with HDP showed a more metabolic condition than the physiological requirement.
Although changes in lipid profile are expected, it is still difficult to determine the cut-off level for diagnosing hyperlipidemia in pregnant women. We combined the diagnostic criteria of dyslipidemia in general Chinese population and clinical data during pregnancy, pregnant women whose TC > 6.20 mmol/L and TG > 2.30 mmol/L or to either of them were diagnosed with hyperlipidemia. Expect for pregnancy complications , maternal dyslipidemia has been proved to be closely linked with adverse pregnancy outcomes including cesarean delivery and postpartum hemorrhage . Consistent with previous researches, we reported that women with hyperlipidemia compared with these in normal lipid group had a higher rate of GDM and cesarean section. In addition, the mean of postpartum hemorrhage both in the GDM and HDP groups was greater than that in the control group. As for the conditions of newborn, evidence shows that dyslipidemia results in an adverse intrauterine environment and can induce excessive fetal growth. Recently, some maternal lipid parameters have been served as independent predictors of fetal overgrowth, especially in women complicated by GDM [28, 29]. The risk of macrosomia was positively related to TG levels, while negatively related to HDL-C levels in non-diabetic pregnancies . However other studies failed to find any association [30, 31]. In the present study, we found that the incidence of macrosomia was significantly increased in the hyperlipidemia group. Meanwhile, the average body length and weigh of newborn in the GDM and HDP groups were significantly lower than those of the control group. Recognizing lipid abnormalities may allow for appropriate risk-reducing interventions of pregnancy complications as well as clinical outcome of mother and fetus.
The associations of increased levels of lipids during gestation with the risk of GDM and HDP have not been clarified [8, 18, 32, 33]. We then to explore whether dyslipidemia in the 2nd trimester has potential clinical utility for identifying women at risk for developing GDM and HDP. Logistic regression analysis showed that AIP was a risk factor of GDM, while TC was a protective factor. Among the Chinese population, Jin et al report that lower levels of HDL-C have a significant association with increased risk of GDM . Our results illustrated that the incidence of GDM was negatively correlated with levels of TC and HDL-C. TC reflects the content of total cholesterol including HDL-C and LDL-C. Taken together, we considered that the proper increase of HDL-C so-called "good" cholesterol, had a protective effect for those with GDM.
The present study was limited by its retrospective design and some possible confounders such as weight and lipid profiles at all gestational stages could not be accounted. A prospective observational design is needed to overcome the limitation of lacking other parameters and corroborate our findings.