What critical period for exposure to Warfarin is associated with potential fetal defects?

The critical period for exposure to Warfarin associated with potential fetal defects is during weeks 6 to 9 of gestation. This timeframe is significant because it corresponds with the period of organogenesis, where many vital organs and structures, including the heart and central nervous system, are developing.

During this time, fetal exposure to teratogenic agents like Warfarin can lead to various defects, including skeletal abnormalities and central nervous system malformations. Since Warfarin is an anticoagulant that can cross the placenta, it poses a risk during this crucial developmental window. It's important for healthcare providers to assess the risks associated with Warfarin exposure during pregnancy and consider alternative anticoagulants when necessary, especially during these early weeks when the risk of teratogenic effects is heightened.

The other timeframes listed do not align with the peak risk of teratogenic effects from Warfarin. The first few weeks of pregnancy, before 6 weeks, are before significant organ development occurs; later weeks, especially after the 10th week, usually entail a diminished risk for structural defects, although Warfarin can still pose risks throughout pregnancy.