Continuous association of total bile acid levels with the risk of small for gestational age infants

The association between maternal serum total bile acid (TBA) levels and small-for-gestational-age (SGA) infants is unclear. We investigated the association between various degrees of serum TBA levels and the risk of SGA infants in a Chinese population. The current study performed a cohort study among 11811 mothers with singleton pregnancy. Subjects were divided into seven categories according to maternal serum TBA levels. Interestingly, birth sizes were reduced, whereas the rate of SGA infants was increased across increasing categories of serum TBA. Compared to category 1, adjusted ORs (95%CI) for SGA infants were 0.99 (0.82–1.21) in category 2, 1.22 (0.97–1.53) in category 3, 1.99 (1.53–2.58) in category 4, 2.91 (2.16–3.93) in category 5, 4.29 (3.33–5.54) in category 6, and 9.01 (5.99–13.53) in category 7, respectively. Furthermore, adjusted ORs (95%CI) for SGA infants for each 1-SD increase in serum TBA levels were 1.36 (1.29–1.43) among all subjects, 2.40 (1.82–3.45) among subjects without cholestasis, and 1.13 (1.06–1.22) among subjects with cholestasis, respectively. These results suggest that gestational cholestasis increases the risk of SGA infants. Additionally, our results indicate strong, continuous associations of serum TBA levels below those diagnostic of cholestasis with a decreased birth sizes and an increased risk of SGA infants.