Secondary causes are far more common than primary ones. One study found that 15% of healthy first-time mothers had low milk supply 2–3 weeks after birth, with secondary causes accounting for at least two-thirds of those cases.Breastfeeding management issues that can interfere with regular milk drainage from the breast include poor latch, unnecessary use of supplemental formula, timed or scheduled feedings (as opposed to on-demand feedings), and overuse of pacifiers. Medical conditions in the infant that result in weak or unco-ordinated sucking can cause low milk supply by inhibiting the transfer of milk to the baby. These conditions include tongue-tie, congenital heart defects,  prematurity, and Down syndrome.Primary causes of low milk supply include:

insufficient glandular tissue, also known as primary lactation failure. Breasts with insufficient glandular tissue often have a tubular shape, with a large space between the breasts, and often do not grow during pregnancy. retained placenta
Sheehans syndrome
prior breast surgery (especially breast reduction)
prior nipple piercing
polycystic ovary syndrome (PCOS)
hypothyroidism
hypoprolactinemia
theca lutein cysts
hypertension
pregnancySmoking more than 15 cigarettes per day is associated with reduced milk production. Many medications are known to significantly suppress milk production, including pseudoephedrine, diuretics, and contraceptives that contain estrogen. It is suspected that some herbs, particularly sage and peppermint, suppress milk production. Mechanism
The physiological mechanisms that regulate breast milk supply are poorly understood. High levels of prolactin are necessary for lactation, however there is no direct correlation between baseline levels of prolactin and quantity of milk production.
One person rejected treatment and died because he couldnt afford to pay for it. Boyer collected data on the cost of production and marketing, and found that the largest true cost to payers, $4100/vial, was that of the legal, regulatory and hospital activities involved in selling the drug. Clinical trials contributed $300/vial, and 25% of that had been paid for by government grants. Other costs were the same as in Mexico. References
External links
RxList: Crotalidae Polyvalent Immune Fab (Ovine)