Uric Acid Increment From Middle Term To Late Pregnancy Is Associated With Pregnancy Induced Hypertension And Neonatal Birth Weight

Background:Hypertensive disorder complicating pregnancy(HDCP)is a common complication specifically occurred during pregnancy.HDCP can cause organ dysfunction,such as liver damage and renal insufficiency,abnormal placental function,and finally lead to adverse prenatal outcomes.Serum uric acid concentration elevates in those suffering HDCP.Uric acid,as the end-product of purine metabolism,is an important antioxidant in human body.The new guidelines(2015)pointed out the reference value of uric acid in diagnosing the disease and assessing its severity.There are extensive literatures on the relationship between uric acid in one term of pregnancy and hypertension.However,the research on the relativity between the uric acid increment in middle and late term of pregnancy and hypertension is few.This article is for the purpose of investigating how serum uric acid concentration changes from the second trimester to the third and if there is a change,whether it is associated with progression of pregnancy hypertension and adverse fetal outcome.Objective:1.Compare uric acid level in the second term and the late between the case group and normal control.Furthermore,make this comparison between preeclampsia group and gestational hypertension group.2.Investigate and compare the change trend of uric acid from the second trimester to the third in the case group and normal control.Also,compare this trend between preeclampsia group and gestational hypertension group.3.Explore the relationship of the change trend of uric acid and the gestational week when blood pressure rising,delivery week and fetal birth weight.4.Explore whether the change extent of uric acid from middle term to the third can be a risk factor of preeclampsia or gestational hypertension.Judge the diagnostic value of uric acid change from the middle trimester to the late of preeclampsia or gestational hypertension.Methods:We conducted a retrospective case control study of 306 pregnant women at Nanjing First Hospital,including 75 women with gestational hypertension,71 women with preeclampsia and 160 normal controls without any obstetric complications.Women with multiple pregnancies,known heart disease,nephropathy,hypertension preceding pregnancy,diabetes mellitus or any other obstetric complications were excluded from this study.Case groups were followed up until 12 weeks after delivery and blood pressure returned to normal.Data were collected from January 2012 to April 2017.Age,blood pressure,gestational week at delivery,and newborn birth weight of all gravidas were recorded.Serum uric acid concentration was measured following 12-hour overnight fast in middle(24-28 gestation week)and late term pregnancy(34-40 gestation week)respectively.All women were from Jiangsu and Anhui province without purine diet.Compare uric acid level in the second term and the late between the case group and normal control and investigate the change trend of uric acid from the second trimester to the third in the case group and normal control.Furthermore,explore the relationship of the change and adverse prenatal outcome and judge the its diagnostic value of preeclampsia or gestational hypertension.The SPSS 21.0 software package were used to perform descriptive statistical analyses.The Graphpad Prism 6.0 were used to draw graphical sheets.P<0.05 was considered statistically significant.Results:1.Uric acid concentration in the second trimester of HDCP group(223.09=t74.31?mol/L)was higher than normal control(192.71±148.19?mol/L)(P<0.001).There was no difference between preeclampsia group(230.46±77.00?mol/L)and pregnancy hypertension group(216.11±71.48?mol/L)(P=0.245).In the third trimester,uric acid level in HDCP group(348.25±91.47?mol/L)was higher than normal control(278.81±73.70?mol/L)(P<0.001).In the preeclampsia group,uric acid concentration in the third trimester(375.64±100.15?mol/L)was higher than pregnancy hypertension(322.32±74.20?mol/L)(P<0.001).2.Uric acid concentration arose from the second trimester to the third in both HDCP group and normal control.Uric acid level increased 125.16±86.68?mol/L in HDCP group and was higher than normal control(87.65±63.73?mol/L)(P<0.001).In the case group,the average increment of preeclampsia(145.18±92.00?mol/L)was higher than pregnancy hypertension(106.21±77.25?mol/L)(P=0.006).Uric acid amplification in HDCP group(64.72±46.40%)was bigger than normal control(48.89±37.44%)(P=0.001).There was no difference between preeclampsia(71.55±45.88%)and gestational hypertension(58.25±46.26%)(P=0.084).3.There was not significant relationship between newborn birth weight and uric acid increment in both preeclampsia and gestational hypertension groups,Spearman correlation coefficient was-0.170(P=0.162)and-0.151(P=0.196)respectively.As a whole,neonate birth weight was negatively related to uric acid increment in the HDCP group(r=-0.204,P=0.014).Uric acid amplification was not related to neonate birth weight in both preeclampsia and gestational hypertension(r1=-0.200,P1=0.100,r2=-0.154,P2=0.187)but generally speaking,it was negatively related to newborn birth weight in the HDCP group(r=-0.217,P=0.009).There was not significant relationship between uric acid increment or amplification and delivery time or gestational week when blood pressure first rising.4.Uric acid increment and amplification were risk factor of HDCP(OR1=1.007,P1<0.001,OR2=1.009,P2=0.002),especially preeclampsia(OR1=1.010,P1<0.001,OR2=1.014,P2<0.001).However,uric acid increment and amplification was not a risk factor of gestational hypertension(OR1=1.004,P1<0.058,OR2=1.006,P2<0.105).5.Uric acid increment had diagnostic value on preeclampsia and Receiver Operating Characteristic(ROC)curve analysis showed the area under the curve(AUC)was 0.704 with a cutoff of 129.80?mol/L.The sensitivity and specificity were 66.20%and 78.06%respectively.Also,uric acid increment had diagnostic value on gestational hypertension(AUC=0.594,P=0.022)with a cutoff of 125.50?mol/L,the sensitivity and specificity were 42.67%and 76.77%respectively.Uric acid amplification had diagnostic value on preeclampsia as well(AUC=0.657,P<0.001)with a cutoff of 71.98%,the sensitivity and specificity were 54.93%and 78.06%respectively.By comparison,uric acid amplification had no diagnostic value on gestational hypertension(AUC=0.552,P=0.222).Conclusion:1.Uric acid concentration was higher in women suffered with HDCP.Uric acid level in the second trimester was not related to the severity of the disease but in the third trimester,uric acid concentration increased as disease became serious.2.Uric acid concentration showed an increased tendency gradually from the second trimester to the third and this tendency in the preeclampsia was more obvious than gestational hypertension.However,the amplification did not change as disease became serious.3.Uric acid increment and amplification from the second trimester to the third had a negative relationship with neonate birth weight in HDCP.4.Uric acid increment and amplification from the second trimester to the third were risk factor of HDCP,especially preeclampsia.Uric acid increment from the middle to the late term of pregnancy had diagnostic value on preeclampsia and gestational hypertension and uric acid amplification had a diagnostic value on preeclampsia only.