Transplacental Passage of Metal Ions in Women with Hip Resurfacing: No Teratogenic Effects Observed

Over recent years, hip resurfacing has been performed in young, active patients, including women in their child bearing years. Current work investigating the transplacental passage of metal ions (cobalt and chromium) suggests significant passage of ions across the placenta in mothers with metal on metal hip resurfacing. In vitro studies show that cobalt and chromium can create DNA and chromosome damage in human cells. The consequences of this ion transfer on the child during fetal development and thereafter have not been fully quantified. We report on 3 patients with metal on metal hip resurfacings who had the prosthesis in situ during pregnancy. Our data show that umbilical cord blood chromium levels are under a quarter of the maternal serum levels. Cord blood cobalt levels are approximately half that of maternal blood. All 3 children are healthy. Although there was transplacental passage of ions, there was no significant effect on the child in these cases. We did not show any teratogenic effect of metal ions on the child, and this is consistent with the reported literature.