We are what we eat. Today we complain our children are disobedient towards us, but why the surprise? If we feed our children haram (even while in the womb) then the thoughts that will be bred in their minds (later in life) will be haram. Understand well, halal foods breed halal thoughts and halal actions whilst haram food breeds haram thoughts and haram actions.
Shaykh Ashraf Ali Thanwi narrates, ‘If before birth of the child, parents were to reform themselves and adopt piety, then there is no reason why the child born too should not be pious. The actions of parents during pregnancy have a profound effect on the unborn child. Accordingly, the son of a saint was quite mischievous. Somebody queried the saint; ‘It is indeed strange; you are so pious yet your son so naughty?’ The saint replied, ‘ One evening I was invited to meals by a rich person (whose income was doubtful). After eating, my nafs became excited and I made love to my wife who became pregnant. This child is the effect of the doubtful food.’
Therefore, during pregnancy (especially) it is of the utmost importance to eat a varied halal diet brought from halal income. If in doubt regarding ingredients, leave it out.
Source: Ashrafs Blessings of Marriage published by Ashrafs Amanat