Check out this article from today's New York Times. Bold, mine.
[A]s pressure to breast-feed increases, a two-class system is emerging for working mothers. For those with autonomy in their jobs-generally, well-paid professionals -breast-feeding, and the pumping it requires, is a matter of choice. It is usually an inconvenience, and it may be an embarrassing comedy of manners, involving leaky bottles tucked into briefcases and brown paper bags in the office refrigerator. But for lower-income mothers - including many who work in restaurants, factories, call centers and the military - pumping at work is close to impossible, causing many women to decline to breast-feed at all, and others to quit after a short time.
It is a particularly literal case of how well-being tends to beget further well being, and disadvantage tends to create disadvantage - passed down in a mother's milk, or lack thereof.