Association of raised blood lead levels in pregnant women with preeclampsia: A study at tertiary centre

Environmental exposure to metal(loid)s and hypertensive disorders of pregnancy: A systematic review

BACKGROUND

Environmental exposure to metal(loid)s has been associated with adverse effects on human health, but the systemic repercussion of these elements on the development of hypertensive disorders of pregnancy (HDP) is still poorly understood.

OBJECTIVE

To summarize evidence published about the influence of environmental exposure to aluminum, arsenic, barium, cadmium, lead, strontium and mercury on the development of HDP.

METHODS

We conducted a systematic literature review according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The search strategy was validated by the Peer Review of Electronic Search Strategies. We searched for articles published up to February 2023 in seven databases without language restriction. Two researchers conducted the steps for selection, data extraction and evaluation of the methodological quality of the instruments for epidemiological studies of the Joanna Briggs Institute. Any disagreements were resolved by a third researcher.

RESULTS

We obtained 5076 records, of which 37 articles met the inclusion criteria moderate to high methodological quality. Single exposure to metal(loid)s was predominant, and the leading biological matrix analyzed to detect the concentrations from exposure was maternal blood. Lead was the metal investigated the most, and had the largest number of studies showing positive association with HDP. In relation to the other metal(loid)s, higher levels were found in women with HDP in comparison with healthy women, but the finding of a cause-effect relationship was inconsistent.

CONCLUSIONS

Although we found evidence of harmful effects of the metal(loid)s studied on human health, the results were inconclusive with regard to HDP. Longitudinal studies that consider prospective investigation, adjustment of confounding factors and the interference of other contaminants in the exacerbation of oxidative stress in women from the preconception phase to the puerperal period should be encouraged.

Urinary protein and coagulation-fibrinolysis indicators in preeclampsia: Expression and significance

This study investigates the expression and significance of urinary protein and coagulation-fibrinolysis indicators in preeclampsia, categorized into mild preeclampsia (109 cases) and severe preeclampsia (97 cases) based on disease severity. Additionally, 110 patients with gestational hypertension (gestational hypertension group) were included for comparative analysis. General information, laboratory indicators, urinary protein, and coagulation-fibrinolysis indicator levels were collected for each group. Significant differences were observed in blood pressure among groups (P < .05), while uric acid, serum creatinine, aspartate transaminase, alanine transaminase, and triglycerides showed no significant differences (P > .05). Total cholesterol, triglycerides, and low-density Lipoprotein levels in severe preeclampsia were higher than those in mild preeclampsia and gestational hypertension groups, whereas high-density lipoprotein, albumin, and platelet levels were lower in severe preeclampsia. No significant differences were observed in prothrombin time or D-dimer levels among groups (P > .05). Urinary protein, urinary protein quantification, activated partial thromboplastin time, thrombin time, and fibrinogen were identified as influencing factors for adverse maternal and infant outcomes in severe preeclampsia patients. The study concludes that urinary protein and coagulation-fibrinolysis indicators are elevated in preeclampsia, particularly in severe preeclampsia cases, suggesting their potential use as diagnostic influencing factors for severe preeclampsia.

A global perspective of correlation between maternal blood lead levels and risks of preeclampsia: An updated systematic review and meta-analysis

Background

Preeclampsia (PE) is a specific hypertensive disorder in pregnancy. Lead (Pb) is a heavy metal that affects women's reproductive health. However, it is unclear whether lead exposure during can predispose maternal risk of developing preeclampsia. This systematic review and meta-analysis study aimed to explore the association.

Methods

We searched studies from three databases (PubMed, Web of Science, Embase). Only case-control, cross-sectional, and cohort studies reporting maternal blood lead levels (BLL) and PE were included from database inception to 31st July 2022. Pregnant women with blood lead levels measured were eligible. Those healthy pregnant women who did not develop preeclampsia were assessed as comparators. Letters, comments, case reports, and reviews were excluded. Newcastle-Ottawa Scale (NOS) and its adaptive form were applied for assessment. The random-effects method (REM) was applied to calculate the standardized mean difference (SMD) with a 95% confidence interval (CI). Stata 16.0 and RevMan 5.3 were the software used for data extraction and analysis.

Results

25 studies out of 1,808 articles made the finalist for systematic reviews, of which 21 underwent further quantity analysis. A total of 1,533 preeclamptic women and 10,998 healthy pregnant controls were included in the meta-analysis. The overall result revealed that maternal lead exposure was significantly higher in women with preeclampsia (SMD: 1.06, 95% CI 0.69, 1.43); (I ² = 96.40%; P = 0.000).

Conclusion

This study demonstrates that maternal lead exposure is associated with preeclampsia during pregnancy. The association is present even in low blood lead levels. The conclusion should be taken seriously and women should avoid unexpected exposure to a lead-containing environment as much as possible.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=347220, identifier: CRD42022347220.

Blood Lead Levels among Non-Occupationally Exposed Pregnant Women in Southern Thailand

Lead (Pb) is a heavy metal that is toxic to humans, especially children and pregnant women. In Thailand, guidelines exist to minimize lead exposure in pregnant women working in lead-related occupations. However, no guidelines exist for pregnant women who are not employed in these economic sectors. This cross-sectional study aimed to examine blood lead levels (BLLs) and related risk factors among 80 non-occupationally exposed pregnant women from the general population living in Nakhon Si Thammarat province, Southern Thailand. BLLs were determined by graphite furnace atomic absorption spectrophotometry. A validated questionnaire was adopted to interview participants which included demographic, consumer goods, supplement intake, and health factors. The mean BLL was 4.68 ± 1.55 µg/dL (95% CI 4.33-5.02) and 42.50% had BLLs ≥ 5 µg/dL. Higher education was the only demographic factor associated with BLLs ≥ 5 µg/dL (aOR 0.16, 95% CI 0.03-0.80, p = 0.027). Systolic blood pressure was also associated with BLLs ≥ 5 µg/dL (aOR 5.00, 95% CI 1.23-17.16, p = 0.023). However, consumer goods and supplement intake were not associated with BLLs. Our results indicate that pregnant women from the general population who were not in the risk exposure group had lead in their bodies. Except for education, demographics were not associated with pregnant women with BLLs. However, with health factors, even low BLLs had a small effect on systolic blood pressure. These data suggest a need for promoting health education and health interventions to prevent the dangers of lead exposure, especially for pregnant women and children.

Lead Levels in Non-Occupationally Exposed Women with Preeclampsia

There are many controversies regarding the relationship between lead exposure andcomplications in pregnancy. Preeclampsia (PE) is a maternal hypertensive disorder which is one of the main causes of maternal and foetal mortality. The aim of our study was to assess blood lead level (BLL) in Polish women with PE (PE group, n = 66) compared with healthy, non-pregnant women (CNP group, n = 40) and healthy pregnant women (CP group, n = 40). BLL was determined by inductively coupled plasma mass spectrometry (ICP-MS). The systolic blood pressure (SBP), diastolic blood pressure (DBP) and BLL in the CP group were significantly lower than in the PE group (p < 0.001). Logistic regression analyses of BLL showed a significant positive relationship with the presence of PE. Furthermore, both the SBP and DBP values were positively associated with BLL. This study indicates that preeclamptic women tend to present with significantly higher BLL compared to healthy pregnant women. There were no differences in the BLL between the CP and CNP groups.

Lead exposure and association with angiogenic factors and hypertensive disorders of pregnancy

OBJECTIVES

Lead exposure has been associated with hypertensive disorders of pregnancy. Angiogenic factors, including soluble fms-like tyrosine kinase 1 (sFlt1) and placental growth factor (PlGF), are aberrant in preeclampsia, but have not been correlated with lead levels. We evaluated the association of lead exposure with angiogenic factors.

STUDY DESIGN

This cross sectional study utilized a convenience sample of singleton pregnancies ≥34 weeks' gestation. Blood lead and angiogenic factors were measured before delivery; bone lead was measured postpartum. We dichotomized bone and blood lead into the top tertile versus the bottom tertiles and used log-binomial regression to assess the association between lead and a high angiogenic ratio.

MAIN OUTCOME MEASURES

The outcomes were high sFlt1 to PlGF ratio and development of a hypertensive disorder of pregnancy.

RESULTS

We enrolled 102 participants, of whom 98 had at least one lead measurement and an angiogenic factor result. Median bone lead was 3.8 ug/g (2.0 - 6.6) and median blood lead was 0.2 ug/dL (0.2 - 0.4). Incidence of hypertensive disorders of pregnancy was 31%. When comparing the highest tertile of bone lead to the bottom two tertiles, there was no association with a high sFlt1/PlGF ratio or hypertensive disorders of pregnancy. Similar results were observed for the exposure of blood lead.

CONCLUSIONS

Lead exposure was not an important contributor to an elevated angiogenic factor ratio or hypertensive disorders of pregnancy in our U.S.

POPULATION

However, lead exposure was modest in our population and we cannot exclude a relationship with hypertensive disorders of pregnancy.