Selective serotonin reuptake inhibitors (SSRIs) are the most common drugs prescribed to treat depression during pregnancy. The influence of SSRI exposure during pregnancy on fetus bone properties is not clearly understood. The overall objective of this thesis project was to investigate the short and long-term effects of in utero and postpartum exposure to SSRIs on bone in rats through measuring bone structural and material properties.

Two studies with two types of SSRIs were carried out. Dams in the treated groups were randomly assigned to receive sertraline (10 mg/kg/day, N=5) in the first study and fluoxetine (10 mg/kg/day, N=17) in the second study. Control animals in the studies received saline in a flavoured gelatin vehicle. Rats were exposed to sertraline only during pregnancy, but fluoxetine was administered to the dams during pregnancy and also during breastfeeding. Rat offspring were sacrificed at 3, 7 and 26 weeks of age and left femurs and L6 vertebrae were analyzed for differences in morphology and mechanical properties.

Maternal sertraline exposure resulted in significantly shorter femurs for the offspring at 3 weeks of age. Rat femurs from the sertraline group were also weaker at 3 and 7 weeks of age compared to controls. In comparison, in utero and postpartum exposure to fluoxetine did not have a negative impact on bone properties. In fact, the femurs from fluoxetine exposed offspring were significantly stronger at 3 weeks of age compared to the controls

Findings in this project suggest that the type of SSRI used by pregnant woman should be considered as an important factor. Maternal sertraline exposure has a negative effect on offspring bone properties. Considering the fact that various mechanisms are involved in the influence of SSRIs on bone, further studies should be conducted to determine the mechanisms of this influence on bone properties in utero and through stages of development.