Abstract Introduction Patients with bipolar affective disorder can be effectively managed with pharmacological intervention. This case report describes a pregnant woman with a ten-year history of bipolar affective disorder that was being treated with lithium, haloperidol and benztropine. Case presentation The patient had a normal pregnancy, but developed an elevated blood pressure and started to lose weight at 36 weeks of gestation. During pregnancy, plasma concentrations of choline and phosphatidylcholine are increased to meet the demands of the foetus. However, our findings in this case included depletion of plasma choline and phosphatidylcholine concentrations. Other unusual outcomes included low placental weight and low infant birth weight. Conclusion This report suggests that the pharmacological management of this patient could possibly account for the findings.