ICP incidence at nearly 3% worldwide, but varies by region
Higher numbers seen in lower-income countries and with gestational diabetes
Intrahepatic cholestasis of pregnancy (ICP) is estimated to affect nearly 3% of pregnant women worldwide, with the highest incidence reported in Asia and the lowest in Oceania, the continent that includes Australia, according to a meta-analysis.
Developed countries with higher income levels also tended to report significantly lower ICP incidences, the number of new cases, than did developing countries with low- or middle-income levels.
Further analyses showed that multiple pregnancies (carrying two or more babies at same time) and gestational diabetes — high blood sugar that develops during pregnancy — significantly associated with a higher frequency of ICP.
“These findings may help health policy-makers to adjust resource allocation and management guidelines in the future,” the researchers wrote.
Highest incidence of ICP reported in Asia, lowest in Oceania
The study, “Global and regional incidence of intrahepatic cholestasis of pregnancy: a systematic review and meta-analysis,” was published in BMC Medicine.
Cholestasis is a liver condition characterized by a slowed or blocked flow of bile — a digestive fluid that helps break down fats and proteins — from the liver into the intestines.
ICP is a form of cholestasis that typically occurs during the third trimester of pregnancy. While cholestasis symptoms usually resolve on their own after pregnancy, ICP can increase the risk of complications for both mothers and their babies.
“The incidence of ICP widely varies among the current original studies from less than 1% to more than 20%,” which “has been mostly attributed to ethnic and environmental factors,” the researchers wrote. However, there is even a “considerable difference between reports from each country.”
Moreover, “there is no consensus on the risk factors of ICP based on the available evidence,” they added.
A team of researchers in Iran set out to estimate the global and regional incidence of ICP by systematically reviewing studies, published up to November 2024, reporting on ICP incidence.
A total of 302 studies, covering nearly 43 million pregnant women, were included in the meta-analysis. Among them, 197 studies were from Asia, 83 from Europe, 28 from North America, eight from South America, and six from Oceania.
Results showed that the overall estimated incidence of ICP was 2.9%, with the highest incidence reported in Asia (3.6%) and the lowest in Oceania (0.6%). South America reported the second highest ICP incidence at 2.7%, and the incidence was 2.5% in Europe and 1.3% in North America.
ICP incidence was significantly higher in low- and middle-income countries than in high-income countries (3.5% vs. 2.1%), and in developing regions than in developed regions (3.4% vs. 2.2%).
“These findings suggest the need for region-specific guidelines to more effectively screen and manage ICP in each region,” the researchers wrote.
Multiple births and gestational diabetes appear to raise risk of ICP
Studies including more than 2,822 participants (their median sample size) had a lower ICP incidence compared with those with fewer participants (1.6% vs. 4.7%), “indicating a trend of overestimation by studies with lower sample sizes,” the team wrote.
When smaller studies were excluded from the analysis, the overall ICP incidence fell to 1.5%, with the highest incidence was reported in South America (5.6%), while the lowest remained in Oceania (0.5%).
Excluding the smaller studies also showed a trend toward an increasing incidence in more recent years, from 1% before 2005 to 1.4% between 2006 and 2015, and 1.8% in the 2016-2024 period.
The researchers then looked into potential factors contributing to differences in ICP incidence between studies.
Statistical analyses considering several potential factors showed that multiple pregnancies and gestational diabetes were significantly associated with a higher ICP incidence. Similar results were observed after excluding the smaller studies.
“The findings of this study provide valuable insights into the current knowledge regarding the association of the quality of public health and socioeconomic variations with the incidence of ICP on a global scale,” the researchers wrote.
As studies with fewer participants tended to overestimate ICP incidence, for “future research focused on a comprehensive evaluation of ICP [incidence], it is advisable to adjust the sample estimates accordingly,” the team concluded.
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