We applied the assay to placental samples from 93 women to assess whether maternal overweight/obesity (OWO) and/or gestational diabetes mellitus (GDM) are associated with changes in placental MAO-A kinetic parameters, and to examine the relationship between placental <i>MAOA</i> mRNA levels and MAO-A catalytic capacity.<h4>Results</h4>Maternal OWO was not associated with changes in V<sub>max</sub> or K<sub>m</sub>, nor was GDM associated with changes in Vmax (all p>0.05). The gene discussed is MAOA; the disease is obesity disorder.