Ruling 2492

Eight conditions must be fulfilled for breastfeeding to cause someone to become maḥram:

1. a child must breastfeed the milk of a woman who is alive. Therefore, if a child breastfeeds some of the required amount of milk from the breasts of a dead woman, it is of no use [i.e. the child does not become maḥram];
2. the woman’s milk must be from a legitimate birth, even if [the conception of the child was] from intercourse that ensued from a mistake (waṭʾ al‐shubhah). Therefore, if, supposedly, a woman produces milk without giving birth, or the milk of a child that was born from fornication is given to another child, the latter does not become maḥram to anyone;
3. the child suckles the milk from the breasts of the woman. Therefore, if the milk is poured into the child’s mouth, it has no effect;
4. the milk must be pure and not be mixed with anything;
5. the amount of milk required for someone to become maḥram must all be related to one husband. Therefore, if a nursing mother is divorced and then marries another man and becomes pregnant by him, and until she gives birth the milk that she has from her first husband remains [in her body], and, for example, before giving birth she breastfeeds the child eight times with the milk that is related to the first husband, and after giving birth she breastfeeds the child seven times with the milk that is related to the second husband, then in such a case, the child does not become maḥram to anyone;
   
6. the child must not vomit the milk. If he does, it has no effect; 
7. the child must be breastfed to the extent that his bones become firm by the milk and the milk has made the flesh of his body grow. If it is not known whether the child has been breastfed to this extent or not, in the event that the child breastfeeds to his fill for one day and one night or fifteen times in accordance with the next ruling, it is sufficient. However, if it is known that the milk has not had an effect on making the bones firm and growing the flesh of the child’s body, even though the child breastfed for one day and one night or fifteen times, then obligatory precaution must be observed; i.e. in such a case, the child must not marry [those who would become maḥram to him by means of breastfeeding], nor must he look at them as maḥrams would; 

8. the child has not completed two years of age. If he is breastfed after he completes two years, he does not become maḥram to anyone. In fact, if, for example, before he completes two years he is breastfed eight times and after that he is breastfed seven times, he does not become maḥram to anyone. However, in the event that more than two years pass from the time a woman gives birth and she still carries milk, then, if she breastfeeds a child, this child becomes maḥram to those who were mentioned above.