Objective: To investigate whether maternal serum levels of adiponectin in the first trimester are altered in pregnancies that subsequently deliver small for gestational age (SGA) neonates. Methods: Maternal serum adiponectin and pregnancy-associated plasma protein A (PAPP-A) were measured at 11–13 weeks’ gestation in 50 singleton normotensive pregnancies that delivered SGA neonates and 300 non-SGA controls. The median adiponectin and PAPP-A levels in the SGA and non-SGA groups, expressed as multiple of the unaffected median (MoM), were compared. Results: The distribution of serum adiponectin was made gaussian by square root (sqrt) transformation. Regression analysis in the non-SGA group demonstrated that for sqrt adiponectin a significant independent contribution was provided by maternal age, weight, smoking status, African and South-Asian racial origin. Each value in the SGA and non-SGA group was then converted into a multiple of the non-SGA median (MoM) after adjustment for maternal characteristics. In the SGA group, compared to the non-SGA controls, median maternal serum PAPP-A was decreased (0.79, interquartile range [IQR] 0.54–1.06 MoM vs. 1.00, IQR 0.71–1.39 MoM) but adiponectin MoM was not significantly different (0.89, IQR 0.65–1.31 MoM vs. 1.02, IQR 0.70–1.29 MoM). Conclusion: Maternal serum adiponectin is not a useful biochemical marker for early prediction of SGA.