Abnormal blood lipid levels linked with ICP, pregnancy complications
More bile acids in bloodstream also linked with greater blood lipid changes
Abnormal levels of certain fatty molecules, or lipids, in the blood appear to increase the risk of intrahepatic cholestasis of pregnancy (ICP) and its complications, a study in China suggests.
Also, higher levels of lipid-digesting bile acids in the bloodstream, a diagnostic biomarker of ICP, were linked to greater changes in blood lipids, further supporting the latter as a possible biomarker.
“In clinical practice, bile acid and blood lipid levels in pregnant women should be closely monitored to improve the diagnosis and early prevention of ICP,” the researchers wrote. “This may improve both maternal and neonatal outcomes.”
The study, “The correlation between blood lipids and intrahepatic cholestasis syndrome during pregnancy,” was published in the Journal of Obstetrics and Gynaecology.
The bile ducts are a network of tubes that take bile from the liver to the small intestine to help digest and absorb fatty molecules in food. In cholestasis, flow through the bile ducts is slowed or stopped, causing bile to build up in the liver and leak into the bloodstream.
Toward the later stages of pregnancy, some women develop ICP, a form of cholestasis. While its symptoms usually resolve on their own after pregnancy, ICP can increase the risk of complications for both mothers and their babies. It’s usually diagnosed by testing a sample of blood for high levels of bile acids, a bile component, and checking how well the liver is working based on levels of liver enzymes.
“However, it has been observed that women diagnosed with ICP often do not exhibit elevated TBA [total bile acid] levels. Additionally, other medical conditions can also lead to increased TBA levels,” the researchers wrote.
Bile acid blood levels “are closely related to lipid metabolism, absorption, and regulation, particularly of cholesterol,” and cholesterol is broken down into bile acids in the liver, the researchers wrote. This supports a close link between bile acid and blood lipid levels.
Are blood lipids an ICP biomarker?
To understand if blood lipids could be an early biomarker of ICP, researchers in China looked at the medical records of 473 pregnant women, ages 20-40, at the later stages of pregnancy who had visited a single Chinese hospital between June 2020 and June 2023. A total of 204 women had ICP and 269 didn’t.
Regarding lipid changes, women with ICP had significantly higher levels of low-density lipoprotein, or LDL (often called the “bad” cholesterol), total cholesterol, apolipoprotein B (APOB), and triglycerides than those without ICP. The ICP group also had significantly lower levels of apolipoprotein A (APOA) and a lower ratio between high-density lipoprotein, or HDL (often called the “good” cholesterol), and LDL, and a lower ratio between apolipoprotein A and APOB.
The researchers also saw significant associations between levels of these fatty molecules and those of liver enzymes and bile acids.
The APOA/APOB ratio was also found to have the best predictive ability, with a cutoff value of 1.4781 allowing the discrimination between women with and without ICP with a sensitivity of 85.9% and specificity of 47.5%. Here, sensitivity refers to how well the APOA/APOB ratio cutoff could correctly identify ICP cases and specificity to the proportion of pregnant women correctly identified as not having ICP.
Further statistical analyses showed that, even after adjusting for potential influencing factors, including age, all these lipids and lipid ratios were identified “as independent risk factors for ICP.”
Among women with ICP, those with gestational diabetes — high blood sugar that develops during pregnancy — had significantly lower HDL levels than those without. Women with hypothyroidism, that is, when the thyroid gland doesn’t produce enough hormones, had significantly lower APOA levels.
Women with ICP and preeclampsia, a pregnancy complication marked by high blood pressure, had significantly higher triglyceride levels than those without preeclampsia, while those with preterm delivery — before 37 weeks of pregnancy — had significantly lower blood levels of HDL and APOA.
Higher blood levels of bile acids were also linked to gestational diabetes, hypothyroidism, and preterm delivery, suggesting a link between bile acids in the bloodstream and greater changes in blood lipids.
“We found that patients with ICP who have higher [blood] bile acid levels tend to have more disrupted lipid metabolism, as well as a higher risk of complications and adverse pregnancy outcomes,” the researchers wrote. “These results have clinical significance, as they suggest that follow-up monitoring of blood lipid changes is beneficial in reducing the risk of complications of cholestasis during pregnancy.” The researchers said it was important to “treat them effectively.”
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