Thicke, 69, passed away from a heart attack in December.
Tanya revealed her husband had undergone a full physical check-up a few weeks before his death to ensure he was healthy and "ready to go" for another child, reported E! News.
"The fact that he touched on the heart and kind of kept emphasising that... My husband went in for a check-up two months later and he had a full clean bill of health," she said.
Tanya adds Thicke's death was so sudden and calls the timing "unbelievable".