We thank Henderson et al for the interest shown in our study and would like to offer our comments in reply.

In our study, we had 1 case of intrauterine fetal death (IUFD) in a woman with dichorionic diamniotic twins’ pregnancy and severe intrahepatic cholestasis of pregnancy (ICP) at 30 weeks of gestation. The patient had been under observation, which included routine fetal monitoring 3 times per a day, in our Department for 1 week before this event. Importantly, a pathologic fetal heart rate monitoring of the dead fetus was documented several hours after a normal heart monitoring of both twins.

In their letter, Henderson et al suggest that this case of IUFD may be related to the 18% difference in fetal growth between the fetuses. Being that the accepted definition for growth discrepancy is 20% of the larger twin’s weight (in this case 1675 g) and that the dead fetus weighted 1369 g, which is compatible with the 56th weight percentile for gestational age, both intrauterine growth restriction (IUGR) and discrepancy do not exist in this case. Moreover, although IUGR is associated with increased perinatal death in twins in all gestational ages, growth discordance alone is not.

Indeed, as Henderson et al rightfully stated, whether or not ICP is associated with increased risk of fetal death is debatable, but the evidence that supports the true existence of such a connection is accumulating, mostly for singleton pregnancies. Geenes et al recently showed in their prospective case-control study that women with severe ICP were at increased risk for stillbirth.

The unpredictable nature of IUFD in pregnancies that are complicated by ICP and reports of abnormal heart tracing in ICP-affected pregnancies led investigators to hypothesize that these cases of IUFD are caused by impaired fetal cardiomyocyte function that resulted in fetal cardiac arrest. Indeed, the bile acid taurocholate was shown to impair the rate of contraction, the synchronicity, and the calcium dynamics of rat cardiomyocytes in a dose dependent manner, which could result in fetal dysrhythmia and in sudden IUFD.

In summary, the data in this case of IUFD that included the facts that the woman had severe ICP, that the dead fetus’s monitoring suddenly became pathologic, that there was no evidence of IUGR, and that the autopsy was normal support the occurrence of a cardiac event attributed to ICP.