Graphs showing the incidence of meconium staining of the amniotic fluid (A) and preterm labour (B) in studies of the relationship between the maternal serum bile acid level and adverse fetal outcomes[2547–49]. The total maternal serum bile acid level was used in all studies except Laatikainen et al[47] (represented by the white bar), where cholic acid only was used (normal range < 5 μmol/L). Serum bile acid level has been categorized as no ICP (< 10 μmol/L), mild ICP (10-40 μmol/L) or severe ICP (> 40 μmol/L) by the authors. One study[25] used fasting maternal bile acids and compared fetal outcomes with the single highest bile acid reading available. The other studies did not specify whether the mothers were fasted. One study[48] compared fetal outcomes to the serum bile acid level from the week before delivery, and the other studies did not specify which serum bile acid level was used.

Graph showing the timing of IUD associated with ICP[13182325313845474856–58]. The arrow represents six additional cases of IUD from two series with no active management reported as a range of gestational ages at the time of fetal death[4546].