Moms choose to breastfeed because they believe this is the most nutritive, safe choice for their precious babes. Breast pumps make it possible to store this liquid gold, but some storage containers are better than others.

Containers made of polycarbonate or PVC (vinyl) plastics have been shown to leach toxins such as bisphenol A (BPA) and phthalates, chemicals associated with hormone disruption, prostate and breast cancer, and other damaging health effects. Those sealable plastic nursing bags designed for storing breast milk are made of polyethylene. Studies published in Early Human Development and Nutrition Review showed no chemical leaching into the milk, but did indicate that milk stored in these bags may lose some nutrients because they cling to the plastic.

The answer is glass jars, any kind as long as it’s cleaned out very well—preferably in the dishwasher on high heat.

Heavy glass canning jars are ideal for canning breast milk. These jars, available in 8-ounce sizes, can withstand cold and heat. This means they can be refrigerated and placed in hot water for heating milk. After pumping, immediately pour breast milk into one of these wide-mouth jars and refrigerate. Be sure to fill the jar only halfway in order to provide room for glass expansion.