The Association between Dyslipidemia and Preterm Birth: A Prospective Cohort Study in The North of Iran

Dyslipidemia characterized by low density lipoprotein cholesterol and risk of preterm Birth: A Mendelian randomization study

BACKGROUND

Preterm birth is the leading cause of neonatal mortality worldwide, and dyslipidemia is associated with preterm birth in observational studies. We use Mendelian randomization (MR) analyses to uncover the causal association between blood lipid levels and preterm birth.

METHODS

We extracted uncorrelated (R2 < 0.001) single-nucleotide polymorphisms strongly associated (p < 5 × 10-8) with blood lipids from genome wide association studies of FinnGen database and UK Biobank participants. Inverse variance weighted method was the main MR analysis. Sensitivity analyses including genetic pleiotropy, heterogeneity, and directionality of causality were conducted.

RESULTS

The study included 115,082 participants with lipid measurements, 8,507 patients with preterm birth. Increasing apolipoprotein B (odds ratio (OR), 1.12[95 % CI, 1.02-1.23]; p = 0.019), low-density lipoprotein cholesterol (OR, 1.11[95 % CI, 1.00-1.22]; p = 0.040), non-high-density lipoprotein cholesterol (OR, 1.12[95 % CI, 1.01-1.24]; p = 0.026), remnant cholesterol (OR, 1.11[95 % CI, 1.00-1.23]; p = 0.047) and total free cholesterol (OR, 1.11[95 % CI, 1.01-1.23]; p = 0.037) were associated with increased risk of preterm delivery. Moreover, triglycerides in low-density lipoprotein were causally associated with the risk of PTB. Our sensitivity analysis yielded robust results, uncovering no evidence of horizontal pleiotropy or reverse causal relationships.

CONCLUSION

Our investigation unveils the adverse impact of dyslipidemia on preterm birth, with a particular emphasis on the detrimental effect of elevated low-density lipoprotein cholesterol.

The association between pregnancy levels of blood lipids and the risk of preterm birth

Preterm labor, a condition associated with various risk factors such as a history of prior preterm birth (PTB) and multiple pregnancies, has recently seen an increasing focus on its potential link with dyslipidemia. This study aims to investigate the relationship between dyslipidemia in expectant mothers and the risks of PTB. We studied 6963 mothers who gave birth at the International Peace Maternal and Child Health Hospital of Shanghai Jiaotong University School of Medicine in 2020, among which, 437 women had PTB. We extracted clinical and lipid data from electronic records, using multivariable logistic regression and restricted cubic spline models to explore the link between lipid concentrations (by quartiles) in pregnancy stages and PTB risk. The PTB rate was 6.3%. Early pregnancy in the PTB group showed elevated ApoA, ApoB, CHOL, LDL, and TG levels compared to controls (all P < 0.05). Late pregnancy showed no notable lipid differences. Multivariable analysis revealed elevated ApoA, TG, higher age, BMI ≥ 28 kg/m2, hypertension, assisted reproductive technology and gestational diabetes as PTB risk factors (all P < 0.05). After adjustments, higher ApoA, ApoB, CHOL and TG levels correlated with increased PTB risk. Using the lowest quartile, the adjusted ORs for early pregnancy's highest quartile of ApoA, ApoB, CHOL and TG were 1.348, 1.442, 1.442 and 2.156, respectively. Our findings indicate that dyslipemia in early pregnancy, including elevated levels of ApoA, ApoB, CHOL and TG, are associated with PTB. Managing lipid abnormalities during pregnancy may help reduce the risk of PTB.

Dyslipidaemia management in pregnant patients: a 2024 update

Over several decades, the approach to treating dyslipidaemias during pregnancy remains essentially unchanged. The lack of advancement in this field is mostly related to the fact that we lack clinical trials of pregnant patients both with available as well as new therapies. While there are numerous novel therapies developed for non-pregnant patients, there are still many limitations in dyslipidaemia treatment during pregnancy. Besides pharmacotherapy and careful clinical assessment, the initiation of behavioural modifications as well as pre-conception management is very important. Among the various lipid-lowering medications, bile acid sequestrants are the only ones officially approved for treating dyslipidaemia in pregnancy. Ezetimibe and fenofibrate can be considered if their benefits outweigh potential risks. Statins are still considered contraindicated, primarily due to animal studies and human case reports. However, recent systematic reviews and meta-analyses as well as data on familial hypercholesterolaemia (FH) in pregnant patients have indicated that their use may not be harmful and could even be beneficial in certain selected cases. This is especially relevant for pregnant patients at very high cardiovascular risk, such as those who have already experienced an acute cardiovascular event or have homozygous or severe forms of heterozygous FH. In these cases, the decision to continue therapy during pregnancy should weigh the potential risks of discontinuation. Bempedoic acid, olezarsen, evinacumab, evolocumab and alirocumab, and inclisiran are options to consider just before and after pregnancy is completed. In conclusion, decisions regarding lipid-lowering therapy for pregnant patients should be personalized. Despite the challenges in designing and conducting studies in pregnant women, there is a strong need to establish the safety and efficacy of dyslipidaemia treatment during pregnancy.

Maternal Hypercholesterolemia May Involve in Preterm Birth

Maternal hypercholesterolemia during pregnancy is associated with an increased risk of preterm birth which is defined as <37 weeks of complete gestation. However, the underlying mechanism for the association between hypercholesterolemia and preterm birth is not fully understood. Macrophage, as one of the largest cell types in the placenta, plays a very critical role in mediating inflammation and triggers labor initiation. Here, we hypothesize that macrophages can uptake maternal excessive cholesterol leading to its accumulation, resulting in a breach of the immune tolerance and precipitating labor.

Dyslipidemia Management in Pregnancy: Why Is It not Covered in the Guidelines?

PURPOSE OF REVIEW

Despite the elevation of lipid values during pregnancy is mostly physiological, evidence suggest that it may be associated with adverse events. This article reviews the characteristics of lipid disorders and the possible management with dyslipidemia in pregnant women.

RECENT FINDINGS

Among many available groups of lipid-lowering drugs, only bile acid sequestrants are approved for the treatment of dyslipidemia during pregnancy. Ezetimibe and fenofibrate might be considered if benefits outweigh the potential risk. Statins are still contraindicated due to the results mainly from animal studies and series of human cases. However, recent systematic reviews and meta-analyses showed that their use may not be detrimental, and in some selected cases may be beneficial. Especially, in some groups of pregnant patients with very high cardiovascular risk-those already after an event, or with established cardiovascular disease, with homozygous familial hypercholesterolemia; in such cases the final decision should weight the potential risk of discontinuation of therapy. Finally, we need to wait for the data with new drugs, including PCSK9 inhibitors and especially inclisiran, which (still hypothetically) might be a very interesting option as it may be used just before the pregnancy and immediately after with the duration of about 9 months between injections. The decisions on lipid-lowering therapy in pregnant patients should be individualized. Despite design and ethical difficulties with such studies, further investigations on dyslipidemia treatment during pregnancy are highly awaited.