Reference standard for serum bile acids in pregnancy.

Area of Science:

• Reproductive Medicine
• Hepatology
• Clinical Biochemistry

Background:

• Obstetric cholestasis (OC) is a pregnancy-specific liver disorder affecting 1 in 200 women, characterized by pruritus and elevated serum bile acids (SBA).
• OC is linked to adverse perinatal outcomes, including premature delivery and stillbirth.
• Current diagnostic thresholds for mild (10-39 μmol/l) and severe (>40 μmol/l) OC are established, but reference SBA values in normal pregnancy are lacking.

Purpose of the Study:

• To establish reference values for serum bile acids (SBA) in healthy pregnant women.
• To investigate potential changes in SBA levels across different trimesters of pregnancy.

Main Methods:

• A cross-sectional analysis of SBA levels was conducted.
• 219 healthy pregnant women with singleton pregnancies and BMI < 40 were recruited from a tertiary referral university teaching maternity hospital.
• SBA levels were measured at 12, 20, 28, and 36 weeks of gestation, and 1-3 days postpartum.

Main Results:

• SBA levels ranged from 0.3 to 9.8 μmol/l in 216 women, with only three outliers.
• No significant changes in SBA levels were observed throughout pregnancy or postpartum.
• The majority of participants were white European, with a median age of 30 and median BMI of 25.

Conclusions:

• Serum bile acid (SBA) levels in uncomplicated pregnancies are consistent and do not increase with gestation.
• The established reference values for diagnosing obstetric cholestasis (OC) appear appropriate.
• Further research could explore ethnic variations in SBA levels during pregnancy.