Hi thanks for your question.
Your wife is 35 weeks pregnant.Chord round neck is not a problem at this stage of prebnancy,as during movement of fetus inside uterus
knots froms and get released of their own with the movement of fetus inside uterus.However knot at term can cause problems either by causing asphyixia or delaying the onset and progress of labour by not allowing baby head to descent down.
I would suggest you not to worry,however remain under constant observation of your gynaecologist.
Hope this answers your question.