Lipoprotein (a) in pregnancy: a critical review of the literature

Trends and consequences of lipoprotein(a) testing: Cross-sectional and longitudinal health insurance claims database analyses

BACKGROUND AND AIMS

Lipoprotein(a) (Lp(a)) is associated with an increased risk of atherosclerotic cardiovascular disease (ASCVD). Our goal was to characterize patients undergoing Lp(a) testing and to assess the impact of Lp(a) testing on treatment changes and subsequent ASCVD events.

METHODS

A cross-sectional and a longitudinal claims data analysis were performed on 4 million patient records in Germany. Patients were followed up for a maximum of 4 years.

RESULTS

In 2015 and 2018, 0.25% and 0.34% of patients were tested, respectively. Testing was more frequent in younger women in the overall population, and in men in the ASCVD population. Patients tested for Lp(a) had more comorbidities and higher ASCVD risk compared to matched control patients. ASCVD hospitalizations were more frequent prior to the first Lp(a) test (5.55 vs 1.42 per 100/person-years). The mortality rate of the Lp(a)-tested cohort and the control group was similar. Mortality was lower in patients with prior ASCVD and Lp(a) testing compared to matched controls with prior ASCVD and no Lp(a) test (2.30 vs 3.64 per 100/person-years, p <0.001). Patients with Lp(a) test received more laboratory examinations and cardiovascular medications and had more visits with specialized physicians.

CONCLUSIONS

Lp(a) testing is rarely performed even in patients with very high cardiovascular risk. Patients tested for Lp(a) have more comorbidities and a higher ASCVD risk. Lp(a) testing is associated with more intensive preventive treatment and with positive effects on clinical outcomes and survival. The data support the value of Lp(a) measurements to characterize ASCVD risk and to improve ASCVD prevention.

Maternal serum markers of lipid metabolism in relation to neonatal anthropometry

OBJECTIVE

The objective of this study is to examine associations between lipids (high-density lipoprotein, low-density lipoprotein, total cholesterol, triglycerides and lipoprotein (a)) measured on average three time points during pregnancy and neonatal anthropometrics.

STUDY DESIGN

Stored samples from a preeclampsia trial measured as part of a case-control study from five US centers (1992 to 1995) were used. The sample included women without pregnancy complications (n=136) and cases of gestational diabetes (n=93), abnormal glucose tolerance (AGT; n=76), gestational hypertension (n=170) and preeclampsia (n=177). Linear regression and linear mixed-effects models estimated adjusted associations between lipids and birth weight z-score, ponderal index (PI), length and head circumference.

RESULTS

Among women without complications, cross-sectional associations between total cholesterol measured at different gestational ages increased PI 2.23 to 2.55 kg m^-3 per-unit increase in cholesterol. HDL was inversely associated with birth length (β's=-2.21 and -2.56 cm). For gestational hypertension, triglycerides were associated with birth weight z-score (β's=0.24 to 0.31). For preeclampsia, HDL was associated with lower birth weight z-scores (β's=-0.49 and -0.82). Women with gestational diabetes or AGT had inconsistent associations. Examining the level changes across pregnancy, each 0.0037 mmol l^-1 increase in HDL was associated with decreased birth weight z-score (β=-0.22), length (β=-0.24 cm) and head circumference (β=-0.24 cm), whereas each 0.028 mmol l^-1 increase in triglycerides was associated with increased birth weight z-score (β=0.13) and head circumference (β=0.19 cm).

CONCLUSIONS

Although associations varied by complications, in general, growth-promoting fuels such as total cholesterol and triglycerides were associated with increased neonatal size, whereas high HDL was associated with smaller size. Maternal HDL that failed to decrease over pregnancy was associated with smaller neonate size.

Feasibility of placenta-derived mesenchymal stem cells as a tool for studying pregnancy-related disorders

The cellular and molecular mechanisms responsible for pregnancy-related disorders remain unclear. We investigated the feasibility of using placenta-derived mesenchymal stem cells (MSCs) as a tool to study such pregnancy-related disorders. We isolated and expanded adequate numbers of cells with characteristic features of MSCs from the chorionic plate (CP-MSCs), chorionic villi (CV-MSCs), and decidua basalis (DB-MSCs) of human term placental tissues. All placenta-derived MSCs expressed pregnancy-associated C14MC microRNA (miRNA) (miR-323-3p). Interestingly, the placenta-specific C19MC miRNAs (miR-518b and miR517a) were clearly expressed in CP-MSCs and CV-MSCs of foetal origin, but were barely expressed in DB-MSCs of maternal origin. Furthermore, expression levels of placenta-specific C19MC miRNAs in CV-MSCs remained stable during the ex vivo expansion process and across different pregnancy phases (first trimester versus third trimester). High-efficiency siRNA transfection was confirmed in twice-passaged CV-MSCs with little toxicity, and microarray analysis was used to screen for miR-518b target genes. Placenta-derived MSCs, especially CV-MSCs, are a potential tool for investigating the role of placental miRNAs in pregnancy-related disorders.

Effects of folic acid supplementation on serum homocysteine and lipoprotein (a) levels during pregnancy

Introduction:There are many ideas concerning the etiology and pathogenesis of preeclampsia including endothelial dysfunction, inflammation and angiogenesis. Elevated levels of total homocysteine (Hcy) and lipoprotein (a) [Lp(a)] are risk factors for endothelial dysfunction. This study aimed to evaluate the effect of high dose folic acid (FA) on serum Hcy and Lp(a) concentrations with respect to methylenetetrahydrofolate reductase (MTHFR) polymorphisms 677C→T during pregnancy.

Methods: In a prospective uncontrolled intervention, 90 pregnant women received 5 mg FA supplementation before pregnancy till 36th week of pregnancy. The MTHFR polymorphisms 677C→T, serum lactate dehydrogenase activity, urine protein and creatinine concentrations were measured before starting folic acid administration. Serum levels of Hcy and Lp(a) were determined before and after completion of folic acid supplementation period.

Results: Supplementation of the patients with FA for 36 week decreased the median (minimum– maximum) levels of serum Hcy from 11.40 μmol/L (4.40-28.70) to 9.70 (1.60-20.80) μmol/L (p=0.001). There was no significant change in serum Lp(a) after FA supplementation (p=0.17). The overall prevalence of genotypes in pregnant women that were under study for MTHFR C677T polymorphism was 53.3% CC, 26.7% CT and 20.0% TT. There was no correlation between decreasing level of serum Hcy in the patients receiving FA and MTHFR polymorphisms.

Conclusion:Although FA supplementation decreased serum levels of Hcy in different MTHFR genotypes, serum Lp(a) was not changed by FA supplements. Our data suggests that FA supplementation effects on serum Hcy is MTHFR genotype independent in pregnant women.

Maternal dietary counseling reduces total and LDL cholesterol postpartum

OBJECTIVE

The aim of this study was to investigate the effects of dietary counseling on blood lipid concentrations during and after pregnancy.

METHODS

Partcipants (N = 256) were randomized into three study groups: dietary counseling with probiotics or placebo and a control group at first trimester of pregnancy. Diet quality was evaluated from food records by an index of healthy eating and total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol, triglycerides, apolipoproteins A-I and B, and lipoprotein (a) were measured at the first and third trimesters of pregnancy and 1, 6, and 12 mo postpartum.

RESULTS

During pregnancy, no differences in lipid values were noted among the groups, but postpartum TC and LDL-C were lower in both dietary counseling groups compared with controls (P = 0.027 and P = 0.012, respectively). Higher points on the healthy eating index, normal weight, and regular exercise were associated with a more favorable lipid profile at 12 mo after delivery.

CONCLUSION

Maternal dietary counseling may lower maternal TC and LDL-C levels postpartum. A healthy lifestyle during pregnancy and postpartum may benefit women's cardiovascular health.

Lipoprotein(a) is not related to markers of insulin resistance in pregnancy

BACKGROUND

Dyslipidemia, a major risk factor for cardiovascular disease is a common finding in patients with type 2 diabetes and among women with gestational diabetes. Elevated levels of lipoprotein(a) [Lp(a)] are linked to increased risk of cardiovascular disease. However, its relationship with insulin resistance, type 2 diabetes and gestational diabetes is controversial and unproven. Here we aimed to clarify whether Lp(a) levels are associated with insulin sensitivity in pregnancy.

METHODS

Sixty-four women with gestational diabetes and 165 with normal glucose tolerance were enrolled in the study. Fasting Lp(a) serum levels were measured in all women at 24-28 weeks of gestation.

RESULTS

In pregnancy, there was no significant difference in serum Lp(a) concentrations between the two groups. Its level did not correlate with markers of insulin resistance (HOMA-IR), insulin sensitivity (HOMA-S%), pancreatic beta-cell function (HOMA-B%) and insulin sensitivity in dynamic conditions (OGIS). In addition, fasting glucose and insulin levels and those throughout an oral glucose tolerance test were independent of Lp(a) concentrations in our study group.

CONCLUSIONS

Lp(a) levels in pregnant women do not differ with respect to the presence or absence of gestational diabetes. Although influenced by some components of the lipid profile, such as triglycerides and HDL-C, insulin resistance in pregnancy is not affected by Lp(a).

The current status of lipoprotein (a) in pregnancy: a literature review

BACKGROUND AND PURPOSE

Lipoprotein (Lp) (a) is a neglected element of the blood lipid profile. It is now recognized as a determinant of coronary heart disease progression and its role in atherosclerosis and its ability to induce thrombosis make it potentially important in the course of normal and complicated pregnancies. Pregnancy involves a major transformation of metabolism to sustain fetal growth. Multiple studies have been conducted on Lp(a) in pregnancy, and it is timely to synthesize and evaluate this evidence.

METHODS AND SUBJECTS

We reviewed the MEDLINE database for all articles published concerning "lipoprotein a" and "pregnancy" from May 2003 to May 2012. A previous comprehensive review assessed the literature up to May 2003.

RESULTS

We critically analyzed 14 studies detailing the effect of complications in pregnancy on Lp(a) profile, and subsequent pregnancy outcomes where available. Studies evaluating the normal metabolic response to pregnancy, pregnancies complicated by pre-eclampsia and intra-uterine growth restriction were reviewed.

CONCLUSIONS

A substantial mass of data has accumulated describing Lp(a) changes in pregnancy. The diversity of study design limits the ability to draw broad-ranging conclusions, but brings into focus the important questions remaining, which we discuss.

Risk factors for cardiovascular disease in women with a history of pregnancy complicated by preeclampsia or intrauterine growth restriction

OBJECTIVE

Women with a history of preeclampsia or intrauterine growth restriction (IUGR) have an increased risk for cardiovascular disease in later life. We determined the presence of traditional and novel risk factors for cardiovascular disease in these women.

METHODS

We studied 256 women with a history of preeclampsia and 59 women with a history of intrauterine growth restriction. Fifty-three women with a history of uncomplicated pregnancy served as controls. We determined values for blood pressure, body mass index, concentrations of cholesterol, high-density lipoprotein cholesterol, triglycerides and lipoprotein (a), and insulin resistance.

RESULTS

Women with a history of preeclampsia exhibited more risk factors for future cardiovascular disease such as dyslipidemia, hypertension, obesity, and increased insulin resistance compared with women with a history of uncomplicated pregnancy. Women with a history of IUGR have higher concentrations of cholesterol and show a tendency to higher BMI, higher triglyceride concentrations, and increased insulin resistance as compared with women with a history of normal pregnancy.

CONCLUSIONS

Preeclampsia or IUGR may represent an early marker for increased risk for early cardiovascular disease.