I will start by saying that while I don't know you or your husband I feel strongly that the relationship is not a healthy one for you. Being made to feel as though doing what is best for you child is ruining your marriage is extremely damaging not just for you but for you daughter. She understands what you are both saying even though she doesn't show her understanding all of the time. Not being supported by her father in the most natural quest for comfort and nutrition means that he is actually doing more damage to her than good by being there. Think of Meslows higher-achy of needs. It's a pyramid and the bottom section is food, water, sleep, air, basically the essentials for human life. Without getting those basic needs met a person cannot go on to the next section which is security of family,security of health and security of resources. Without those things being fulfilled they can again not go on to feel loved by family and friends. The pyramid continues on. My point is that if she feels that her father is trying to take away her first basic need than you can't feel secure in her relationship with him or loved. She is going to become more and more attached to you and more and more detached from him. This pyramid accurately explains why when a child is weaned early they often harbor resentment and anger. They tend to want to nurse more often and for longer amounts of time, they are whinny and clingy. They feel as though their mother or father is trying to take away something that is a survival tool for them. If he is serious about being a part of the family than he needs to fix his relationship with your and his daughter by putting an end to the weaning discussion. It's not his place to control that aspect of parenting in any way shape or form.
Now on to why extended breastfeeding is best (yes there is a real reason the World Health Organization recommends breastfeeding until 2 years and beyond):
In the second year (12-23 months), 448 mL of breastmilk provides:
29% of energy requirements
43% of protein requirements
36% of calcium requirements
75% of vitamin A requirements
76% of folate requirements
94% of vitamin B12 requirements
60% of vitamin C requirements
-- Dewey 2001
The American Academy of Family Physicians notes that children weaned before two years of age are at increased risk of illness (AAFP 2001).
Antibodies are abundant in human milk throughout lactation" (Nutrition During Lactation 1991; p. 134). In fact, some of the immune factors in breastmilk increase in concentration during the second year and also during the weaning process. (Goldman 1983, Goldman & Goldblum 1983, Institute
of Medicine 1991).
Breastfeeding can be helpful for preventing allergy by:
reducing exposure to potential allergens (the later baby is exposed, the less likely that there will be an allergic reaction),
speeding maturation of the protective intestinal barrier in baby's gut,
coating the gut and providing a barrier to potentially allergenic molecules,
providing anti-inflammatory properties that reduce the risk of infections (which can act as allergy triggers).
Nursing toddlers are SMART
Extensive research on the relationship between cognitive achievement (IQ scores, grades in school) and breastfeeding has shown the greatest gains for those children breastfed the longest.
"Research reports on the psychological aspects of nursing are scarce. One study that dealt specifically with babies nursed longer than a year showed a significant link between the duration of nursing and mothers' and teachers' ratings of social adjustment in six- to eight-year-old children (Ferguson et al, 1987). In the words of the researchers, 'There are statistically significant tendencies for conduct disorder scores to decline with increasing duration of breastfeeding.'"
The American Academy of Family Physicians recommends that breastfeeding continue throughout the first year of life and that "Breastfeeding beyond the first year offers considerable benefits to both mother and child, and should continue as long as mutually desired." They also note that "If the child is younger than two years of age, the child is at increased risk of illness if weaned." (AAFP 2001)
I want you to see her that all sources lay claim to the fact that the mother and child should continue nursing until they feel they are ready. There is no talk of when the other parent is ready, that is because there is no place for a father in the nursing relationship. The father is there to provide emotional and physical support in other ways not to be a part of the breastfeeding relationship.
I wish you luck and I want you to know that you can do this on your own. I am a single mother and have been since my daughter was born. Don't stay with someone when there is nothing there for you or your daughter. It sounds as though this relationship is damaging to you both..