According to the American Academy of Pediatrics 2006 Redbook: Women with tuberculosis who have been treated appropriately for 2 or more weeks and who are not considered contagious may breastfeed. Women with tuberculosis disease suspected of being contagious should refrain from breastfeeding or any other close contact with the infant because of potential transmission through respiratory tract droplets (see Tuberculosis, p 678). Mycobacterium tuberculosis rarely causes mastitis or a breast abscess, but if a breast abscess caused by M. tuberculosis is present, breastfeeding should be discontinued until the mother no longer is contagious. In areas where BCG vaccination is the standard of care, the WHO provides treatment recommendations and advises mothers to continue breastfeeding. TBC may be congenital, or perinatally acquired through airborne droplet spread. HIV
Research published in the Lancet has highlighted a lower risk of HIV transmission with exclusive breastfeeding by HIV positive mothers (4% risk), compared to mixed feeding (10-40% risk). Research on the timing of HIV transmission in 2000 revealed that a "substantial transmission occurs early during breastfeeding," concluding that 75% of all breast milk transmission had occurred within the first 6 months during a randomized control trial in Kenya. This research is of particular importance in developing countries where infant formula is not widely available or safe to prepare. In fact, the World Health Organization recommended breastfeeding in 1987 and 1992 for seropositive and seronegative women in areas where malnutrition and infectious diseases are the major cause of infant mortality.
Breastfeeding difficulties refers to problems that arise from breastfeeding, the feeding of an infant or young child with milk from a womans breasts. Although babies have a sucking reflex that enables them to suck and swallow milk, and human breast milk is usually the best source of nourishment for human infants, there are circumstances under which breastfeeding can be problematic, or even in rare instances, contraindicated. Difficulties can arise both in connection with the act of breastfeeding and with the health of the nursing infant. Breastfeeding problems
While breastfeeding difficulties are not uncommon, putting the baby to the breast as soon as possible after birth helps to avoid many problems. The policy of the American Academy of Pediatrics on breastfeeding instructs to, "delay weighing, measuring, bathing, needle-sticks, and eye prophylaxis until after the first feeding is completed." Many breastfeeding difficulties can be resolved with research based hospital procedures, properly trained nurses and hospital staff, speech pathologists and lactation consultants. Another source of information is the volunteer-based breastfeeding promotion organization, La Leche League. A variety of factors and conditions can interfere with successful breastfeeding:

Ankyloglossia (tongue tie)
Formula feeding
Distractions or interruptions during feeds
Long separations from the mother
Tachypnea (rapid breathing) such as in transient tachypnea of the newborn, surfactant deficiency, respiratory distress syndrome or other infant medical conditions
Presence of an actual physical barrier between mother and infant
Swallowing difficulties such as with prematurity and coordination of sucking, swallowing and breathing, or gastro-intestinal tract abnormalities like tracheo-oesophageal fistula. Pain resulting from surgical procedures like circumcision, blood tests, or vaccinations.