Simple Bile Acid Blood Test Predicts Stillbirth Risk

Intrahepatic cholestasis of pregnancy (ICP) is caused by a build-up of bile acids in the blood, and symptoms include pruritus. ICP is a liver disorder affecting approximately 5,300 pregnancies annually in the UK, more than 14 every day.

ICP is diagnosed in women with gestational pruritus and increased serum bile acids, and can be complicated by preterm labor, fetal asphyxia, meconium-stained amniotic fluid, and stillbirth. It was previously thought that small increases in bile acid concentration are associated with higher risks of stillbirth. Pregnant women showing symptoms of ICP, therefore, are often offered early induction of labor at around 37 weeks in order to prevent stillbirth.

A large team of international scientists collaborating with Kings College London (London, UK) analyzed more than 170,000 pregnancies from 40 international studies to understand the link between ICP, bile acid levels and stillbirth. The results of the study show that for the majority of women with ICP, who have bile acid concentration below 100 μmol/, the risk of stillbirth is not significantly greater than that of pregnant women without ICP. This means they need no further treatment other than regular bile acid blood tests for the remainder of their pregnancy.

The scientists reported that stillbirth occurred in 45/4,936 (0.83%) of intrahepatic cholestasis of pregnancy cases and 519/163,947 (0.32%) of control pregnancies (odds ratio [OR] 1.46). In singleton pregnancies, stillbirth was associated with maximum total bile acid concentration (area under the receiver operating characteristic curve [ROC AUC] 0.83), but not alanine aminotransferase (ROC AUC 0·46). For singleton pregnancies, the prevalence of stillbirth was 3/2,310 (0.13%) of intrahepatic cholestasis of pregnancy cases in women with serum total bile acids of less than 40 μmol/L versus 4/1,412 (0.28%) of cases with total bile acids of 40–99 μmol/L (hazard ratio [HR] 2.35), and versus 18/524 (3.44%) of cases for bile acids of 100 μmol/L or more (HR 30.5).

Caroline Ovadia, BCh, a Clinical Lecturer and first author of the study, said, “This marks a real step forward in the diagnosis and management of liver disorders during pregnancy. Being able to measure the risks to women and their babies by simple tests allows doctors to concentrate treatment on those who really need it. It also means that women will not have to be offered preterm birth unnecessarily which comes with associated risks to their babies including admission to neonatal units, breathing problems and jaundice.” The study was published on February 14, 2019, in the journal The Lancet.

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