The Association Between Urinary Heavy Metal Levels In Pregnant Women And Blood Pressure During Pregnancy

Pregnancy-induced hemodynamic adaptations and hormonal changes lead to increased blood pressure during pregnancy,and pregnant women are more sensitive to environmental factors affecting blood pressure.Further,high blood pressure during pregnancy can signal a greater risk of later-life maternal cardiovascular disease and also enhances risk of adverse birth outcomes such as fetal growth restriction,placental abruption,premature labor,low birth weight,metabolic disease in children and adults.Therefore,exploring the factors of blood pressure during pregnancy is of great significance to maternal and fetal health.With the development of economy and urbanization,mining,metallurgy and chemical industries,heavy metal pollution in China is becoming more and more serious.Some studies have shown that exposure to toxic heavy metals such as lead and arsenic during pregnancy is related to gestational blood pressure.However,there are few studies on the relationship between other toxic metals such as cadmium,thallium and chromium and blood pressure during pregnancy in pregnant women in China.And pregnant women are commonly exposed to multiple metals simultaneously.At present,there are few reports on the association between multiple metal exposures and blood pressure during pregnancy.Therefore,based on the prospective and large-scale birth cohort,this study explored the epidemiological factors of blood pressure during pregnancy and the relationship between the levels of 15 heavy metals in the urine during pregnancy and gestational blood pressure.Part1: Influencing factors of blood pressure during pregnancyObjective: This study aimed to evaluate the trend of gestational blood pressure with gestational weeks,and to analyze the factors that may be related to blood pressure during pregnancy.Methods: Based on the Healthy Baby Cohort(HBC)study,this study involving 15617 participants was conducted in Hubei Province,China,in 2012–2016.The demographic information of pregnant woman was obtained from questionnaire and medical records.Blood pressure data was acquired from hospital information system and maternal health manual.The generalized additive model was used to evaluate the trend of blood pressure during pregnancy with gestational age,and the mixed linear model was applied to analyze the possible influencing factors of blood pressure during pregnancy.Results: The overall trend of systolic and diastolic blood pressure changes with gestational weeks during pregnancy is that blood pressure has a rising stage in early pregnancy,remains unchanged in middle pregnancy and rises rapidly the in late pregnancy.Compared to pregnant women with normal weight before pregnancy,the gestational systolic blood pressure and diastolic blood pressure of overweight pregnant women increased by 3.97 mmHg and 2.17 mmHg,respectively.Older pregnant women have higher blood pressure during pregnancy.The pregnancy women with passive smoking during pregnancy increased diastolic blood pressure by 0.41 mmHg compared with non-passive smoking.Compared with those without gestational diabetes mellitus,the systolic and diastolic blood pressures of pregnant women with gestational diabetes mellitus increased by 1.19 mmHg and 0.76 mmHg,respectively.Compared to nulliparous women,the parous women systolic and diastolic blood pressure during pregnancy decreased by 1.38 mmHg and 1.27 mmHg,respectively.The systolic and diastolic blood pressures of pregnant women with high annual household income were 0.89 mmHg and 1.04 mmHg lower than those of pregnant women with low family income.Conclusions: Pre-pregnancy overweight,maternal age,passive smoking during pregnancy,and gestational diabetes mellitus were positively correlated with gestational blood pressure.The parity and annual family income were negatively correlated with blood pressure during pregnancy.The findings suggest that gestational blood pressure may be affected by pre-pregnancy BMI,maternal age,gestational diabetes mellitus,parity,and annual household income.Part2: The association between urinary heavy metal levels in pregnant women and blood pressure during pregnancyObjective: To evaluate the relationship between maternal urinary heavy metal exposure levels and the blood pressure in early,middle and late pregnancy.Methods: This study involved 2859 pregnant women with heavy metal data in early pregnancy from the Healthy Baby Cohort,during 2014 to 2016.Inductively coupled plasma mass spectrometry(ICP-MS)was used to detect the concentration of heavy metals in urine.The concentration of heavy metals in the urine was corrected by urine creatinine,and its normality was corrected by natural logarithmic transformation.Multiple linear regression models were applied to assess association between urinary heavy metal levels in pregnant women and blood pressure during pregnancy.Multi-metal models were conducted to investigate the impacts of co-exposure to various metals.Confounding factors for adjustment included pre-pregnancy BMI,maternal age,parity,passive smoking during pregnancy,fetal gender,annual family income,pregnancy work,menarche age,and gestational diabetes mellitus.Results: The levels of vanadium,manganese,copper and lead in urine during early pregnancy are related to blood pressure during pregnancy.The higher concentration of urinary vanadium in early pregnancy and lower systolic blood pressure in late pregnancy(V: β=-0.87,95%CI:-1.53,-0.20).The higher urinary manganese concentration,the higher systolic blood pressure in early pregnancy(β=0.51,95%CI: 0.05,0.98).Diastolic blood pressure in early and late pregnancy was higher in those with higher urinary copper in early pregnancy(β=0.65,95%CI: 0.17,1.12,β=0.47,95%CI: 0.13,0.80,respectively).Higher urinary lead concentration in early pregnancy,higher diastolic blood pressure in early and middle pregnancy(β=1.10,95%CI: 0.58,1.62,β=0.45,95%CI: 0.08,0.82,respectively).Higher urinary vanadium concentration in early pregnancy,lower diastolic blood pressure in early and middle pregnancy(β=-1.44,95%CI:-2.24,-0.63,β=-0.59,95%CI:-1.17,-0.02).Conclusions: The level of manganese in urine was positively related with systolic blood pressure in early pregnancy.The level of copper in urine was positively related with diastolic blood pressure in early and late pregnancy.The level of lead in urine was positively related with diastolic blood pressure in early and middle pregnancy.The level of vanadium in urine was negtively related with blood pressure during pregnancy.It is suggested that exposure to manganese,copper,lead and vanadium in early pregnancy may affect gestational blood pressure.