Prevalence and risk factors of intrahepatic cholestasis of pregnancy in a Chinese population

Studies on the risk factors for intrahepatic cholestasis of pregnancy (ICP) in a population-based cohort are lacking. We assess the prevalence and risk factors of ICP in a Chinese population. In this study, a cohort study was conducted that included 12,200 eligible pregnant women. The overall incidence of ICP in this cohort was 6.06%. With increasing maternal age, the incidence of ICP decreased in women younger than 30 years of age but increased in those older than 30. With increasing pre-pregnancy BMI, the incidence of ICP decreased if the pre-pregnancy BMI was less than 23 kg/m(2) but increased if it was 23 kg/m(2) or higher. Further analysis showed that the risk of ICP increased when maternal age was < 25 years (Adjusted RR 2.01; 95% CI 1.64–2.47) or ≥ 35 years (Adjusted RR 1.34; 95% CI 1.02–1.76). Furthermore, an increased risk of ICP was associated with pre-pregnancy underweight (adjusted RR 1.27; 95% CI 1.04–1.56), inadequate gestational weight gain (GWG) (adjusted RR 1.58; 95% CI 1.28–1.96), lower maternal education (adjusted RR 2.96; 95% CI 2.35–3.74), multiparity (adjusted RR 1.54; 95% CI 1.23–1.93), and twin/multiple pregnancies (adjusted RR 2.12; 95% CI 1.25–3.58). Maternal age (< 25 or ≥ 35 years), underweight, inadequate GWG, lower maternal education, multiparity, and twin/multiple pregnancies were identified as risk factors of ICP.