Objective: To evaluate the association between intrahepatic cholestasis of pregnancy (ICP) and gestational diabetes mellitus (GDM).
Study design: A retrospective case-control study of pregnancy outcomes in 57,724 women managed at a university teaching hospital in Rhode Island, USA, in whom universal screening for GDM had been performed and who were assessed for the incidence of ICP. Pregnancies complicated by ICP or GDM between February 2005 and June 2011 were identified from the electronic patient records using appropriate ICD codes. A total of 125 cases were required to detect a difference in the incidence of GDM in ICP at 5% significance with 80% power. Demographic and clinical outcome data (including maternal age, ethnic group, BMI, and infant weight and gender) were also collected.
Results: Of the 57,724 pregnancies, 143 were complicated by ICP (0.25%) and 4880 by GDM (8.5%). Nineteen ICP cases had GDM. The incidence of GDM in ICP was 13.6% (19/140, OR 1.68 CI 1.04-2.72). Where gestational ages were available (n=105), of those screened for GDM prior to developing ICP, 13.4% (11/82, OR 1.64 CI 0.88-3.06) had a confirmed diagnosis, rising to 30% (7/23, OR 4.69 CI 1.98-11.1) in cases that were screened following the onset of cholestasis. Simple linear regression analysis of adjusted birth weight centiles in ICP revealed a significant linear trend of increasing centiles with gestational age (p=0.005).
Conclusions: These data support the hypothesis that the incidence of GDM is higher in women predisposed to developing ICP. It is likely that this susceptibility increases further following the onset of cholestasis.
Keywords: Bile acids; Gestational diabetes; Glucose tolerance; Intrahepatic cholestasis of pregnancy.
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