As the body adjusts to the supply and demand of the child, and as the child itself becomes more proficient at nursing, a woman's breasts will appear to stop producing enough milk. Engorgement, over-active letdown, and regular leaking will diminish and may stop entirely. This is normal. However, there are times when a woman's milk supply will decrease on its own. If the demand for the milk lessens, which could be caused by a mother returning to work or a baby going on a nursing strike, the breasts will supply less milk.
Stresses are a common factor of diminished supply.
A nursing mother who becomes pregnant may find her milk supply decreasing as her body switches its attention to feeding the new fetus. The important thing is to nurse as frequently as possible and maintain a dedication and determination to breast feed. Reduce your stress level. Probably the most overlooked factor of any change in the body is the lack of quality relaxation and a stress-free environment. Delegate tasks, put projects to the side until the breast milk supply is back under control.