Is bagged salad safe during pregnancy?

What does the evidence say about bagged salad during pregnancy?

1. A 2015 to 2016 listeriosis outbreak traced to packaged leafy green salads sickened 19 people in the United States and 14 in Canada, hospitalized every US patient, and killed one, with a further three deaths in Canada. 1
2. That outbreak spanned 22 varieties of packaged salad under six US brands and two Canadian brands, and one case in a pregnant woman ended in a preterm live birth. 1
3. How much washing reduces contamination varies by produce type, which is why rinsing a pre-washed bag at home is not a reliable safety step. 1
4. Bacterial counts on ready-to-eat leafy salads rose by about one log unit across shelf life at 4°C, and after opening plus two days of home storage every sample exceeded a million colony-forming units per gram. 2
5. In a retail survey, pre-packed vegetable salads carried no Listeria at all while pre-packed chicken salads carried it in 6.3 percent of samples, so the added protein is where the risk concentrates. 3

Is bagged salad safe in each trimester?

• First trimester. If salad is one of the few things that appeals, keep eating it. What changes is the buying pattern: smaller bags, bought cold, eaten within a day or two of opening rather than picked at across a week. The bag is not the risk so much as the time it spends open.
• Second trimester. Bagged salad is often the base of a work lunch now. Once a bag is opened, counts climb faster, so decanting the whole thing into a container on Sunday for the week is the habit worth dropping. Buy two small bags instead of one large one.
• Third trimester. Convenience wins late in pregnancy and that is fine. Check that the bag is genuinely cold in the case, not sitting under a lamp or at the front of an over-full shelf, and skip any bag with liquid pooling in the bottom or leaves that have started to go translucent.