The causes of intrahepatic cholestasis of pregnancy are still not fully understood, but are thought to be caused through a combination of
genetic,
hormonal, and environmental factors. • ICP commonly occurs in the
third trimester at the time when hormone levels are at their highest. •
Twin and triplet pregnancies, which are associated with higher hormone levels, show a higher incidence of ICP. • ICP resolves quickly after delivery, when
placental hormone production ceases. • Older high-dose estrogen
oral contraceptive pills could cause features of ICP.
Estrogens Estrogens, and particularly
glucuronides such as estradiol-17β-D-glucuronide, have been shown to cause cholestasis in animal studies, by reducing
bile acid uptake by
hepatocytes.
Progesterone Treatment with progesterone in the third trimester of pregnancy has been shown to be associated with the development of ICP, and levels of metabolites of progesterone, particularly
sulfated progesterone, are higher in patients with ICP than unaffected women, suggesting that progesterone may have a bigger role than estrogen in ICP.
Genetic factors Clustering of cases of ICP in families, geographic variation in rates of ICP, and recurrence of ICP in 45-70% of subsequent pregnancies all suggest a genetic component to the disease. Genetic mutations affecting hepatic bile salt transport molecules have also been found in patients with
progressive familial intrahepatic cholestasis. It has been found that mothers of patients with this disease have a higher incidence of ICP, suggesting that
heterozygote carriers of these mutations are also predisposed to ICP. and high levels of progesterone to inhibit the ABCB4 (MDR3) phospholipid transporter. Consequently, both genetic mutations in hepatocyte proteins involved in bile secretion together with inhibition of those proteins by high levels of hormone metabolites in pregnancy may have roles in the pathogenesis of ICP. • The incidence of ICP in
Chile has dropped from 14% of pregnancies before 1975 to 4% in 2016. • ICP recurs in between 60% and 90% of subsequent pregnancies. • Low serum
selenium levels have been linked to ICP, although the role of selenium in bile secretion is not known. ==Diagnosis==