Abstract: Objective To study the changes of blood lipids during pregnancy,explore the correlation of blood lipids with the weight gain in second and third trimester.Methods From January to June 2019,about 200 pregnant women were selected from the first trimester(8-12 weeks),the second trimester(24-28 weeks) and the third trimester(32-36 weeks). The general information and body wight gain of the subjects was collected and Blood lipidtriglycerides(TG),total cholesterol(TC),low density lipoproteincholesterol(LDL-C),and high density lipoprotein-cholesterol(HDL-C) ,Apolipoprotein A(APOA),Apolipoprotein B(APOB)concentrations were detected during pregnancy.Results ① The blood lipid levels increased with progress of gestation in the investigated pregnant women. The TG concentrations in first,second and third trimester were(1.16 ±0.41) mmol/L,(2.42 ±0.91)mmol/L,and(3.15 ±1.17) mmol/L(P<0.05),respectively. The TC concentrations in first,second and third trimester were(3.85 ±0.69) mmol/L,(5.39 ±0.97) mmol/L,and(6.03 ±1.15) mmol/L,respectively. ②The fast blood glucose,age,and BMI in the lipid disorder group were higher than the normal group in first trimester(P<0.05). ③In the second trimester,there was no statistical difference in age,pre-pregnancy BMI(body mass index),body weight gain in recent one month and total weight gain between TG and TC abnormal group and TG and TC normal group(P>0.05). In the third trimester,the total weight gain in TG abnormal group was higher than that in the normal group. The total weight gain and weight gain in recent one month in TC abnormal group were higher than those in the normal group(P>0.05,both).Conclusion The blood lipid level of pregnant women gradually increased with the prolongation of gestational weeks,however,in the second trimester,blood lipid levels were not associated with weight gain. In the third trimester,the TC concentration was associated with weight gain. The relationship between blood lipid levels during pregnancy and weight gain still needs more research.