Five of the trustees who originally voted to accept sponsorship have resigned but a spokeswoman for the charity said their decision was not connected to the about-turn following the row about Sainsbury's own breast- milk substitute and they they had wanted to leave following "a difficult year".
She insisted there was no dispute between NCT and the trustees, who include Ruth Stone, the chair, Jane Langridge, the treasurer, and Janet Neale, the secretary, and said they were still active in their support for the NCT.
The charity sent out a questionnaire about sponsorship to its members after trustees voted to accept sponsorship from Sainsbury's, which sells its own baby-milk substitute.
Although Sainsbury's does not manufacture the formula, it sells it under its own label which many members felt could be seen as endorsing the store's own-brand formula and thus compromise the position of a charity which strongly promotes breastfeeding.
The results of the survey showed the NCT was split down the middle with 43 per cent of the volunteer workers in favour of sponsorship and 46 per cent against.
But among those who had had training about breastfeeding the figure was 79 per cent against.
It is believed the trustees felt forced to resign in the face of such overwhelming opposition.
Earlier this year, 40 breast-feeding counsellors resigned over the issue and some went on to form a rival organisation, the Breastfeeding Network. It is unlikely they will return.
Caroline King, a member of the trust who was against the sponsorship deal, said she was pleased at the change of heart but saddened at the cost to the NCT.
"We have lost a great deal of talent and experience and we are not going to get it back," she said.
"This began because there was a need for more and more money which got out of control and it felt as if we did not care how we got this money as long as we did get it.
"It has split the NCT in half and I do not know if it will recover."