Cumulative bile acid exposure linked to fetal heart strain in pregnancy condition

A new prospective study suggests that this snapshot approach may miss something important: how much bile acid the fetus is exposed to over time.

The research, published in BMC Pregnancy and Childbirth, followed 248 women with singleton pregnancies affected by the condition at a single center between January 2023 and August 2024. In total, the cohort contributed 1,042 bile acid measurements and 728 cardiac scans.

From these repeated measurements, the team calculated a time-weighted mean bile acid level, an area under the curve, the amount of time spent above 40 and above 100 micromoles per litre, and the conventional peak and final values. The average time-weighted level across the cohort was 36.0 micromoles per litre, with a standard deviation of 17.2. Peak values fell below 40 in 48.4 percent of participants, between 40 and 99 in 37.9 percent, and reached 100 or above in 13.7 percent.

The central finding concerned fetal cardiac function. Each one-standard-deviation increase in the time-weighted bile acid level, equivalent to 17.2 micromoles per litre, was associated with a higher, meaning worse, modified myocardial performance index, with a beta coefficient of 0.022 and a 95 percent confidence interval of 0.011 to 0.033. The relationship was not strictly linear: the analysis detected a nonlinearity at levels of 100 micromoles per litre or above, with a p value of 0.03.

Adverse outcomes were common in this cohort. A composite adverse perinatal outcome, the study’s secondary endpoint, occurred in 76 of the 248 participants, or 30.6 percent. The composite nature of this endpoint means it aggregated multiple types of complications rather than tracking any single event.

When the researchers modeled the odds of the composite outcome, the time-weighted bile acid measure again outperformed the traditional peak. Each standard deviation increase in the time-weighted level carried an adjusted odds ratio of 1.47, with a 95 percent confidence interval of 1.16 to 1.86 and a p value of 0.001. The peak measurement showed a weaker association, with an odds ratio of 1.22 and a confidence interval of 1.01 to 1.48.

Perhaps the most intriguing result came from mediation analysis. The modified myocardial performance index appeared to mediate 21 percent of the association between time-weighted bile acid exposure and the composite adverse outcome, with a confidence interval of 8 to 39 percent and a p value of 0.004. This statistical finding suggests that impaired fetal cardiac function may be one pathway through which sustained bile acid exposure relates to perinatal complications, though mediation models in observational data cannot prove causation.

The authors conclude that dynamic bile acid exposure, particularly the time-weighted mean, was linked to impaired fetal myocardial performance and higher odds of adverse perinatal outcomes. They propose that serial bile acid testing combined with fetal cardiac assessment could sharpen risk stratification for this condition, which currently relies on coarser thresholds.

Important caveats apply. The study was conducted at a single center, and the authors explicitly state that multicenter validation is warranted before these findings change clinical practice. As an observational cohort, the analysis identifies associations rather than proven causal effects, and the composite outcome endpoint pools heterogeneous events. The article was published as an open-access paper on 28 October 2026, and the version shared ahead of final publication remains subject to editorial revision.

For clinicians and researchers, the study adds a dimensional argument to an ongoing debate: not just how high bile acids rise, but how long they stay elevated, may shape what happens to the fetal heart. Whether repeated monitoring and time-weighted metrics can be implemented widely, and whether they improve outcomes when used to guide decisions, will require the larger, multi-center trials the authors call for.

Subject of Research: Dynamic total bile acid exposure and fetal myocardial performance in intrahepatic cholestasis of pregnancy

Article Title: Association between dynamic exposure to total bile acids and fetal myocardial performance index with perinatal outcomes in intrahepatic cholestasis of pregnancy

Article References: Liu, H. (2026). Association between dynamic exposure to total bile acids and fetal myocardial performance index with perinatal outcomes in intrahepatic cholestasis of pregnancy. BMC Pregnancy and Childbirth. https://doi.org/10.1186/s12884-026-09954-w

Image Credits: AI Generated

DOI: 10.1186/s12884-026-09954-w

Keywords: intrahepatic cholestasis of pregnancy, total bile acids, fetal myocardial performance index, perinatal outcomes, risk stratification, prospective cohort, mediation analysis, obstetrics, fetal cardiology, bile acid monitoring, Association, between