More great reader questions this week. Here are some answers.
From Deli Meat Lover:
Are all deli meats a no-go? Or can I continue to eat fancy soppressata sandwiches?
The place to start on this is to figure out why deli meats are off limits. The answer is listeria, a very dangerous foodborne illness. Listeria grows well at room temperature, so things like deli meats that sit around in display cases for a long time can be susceptible. It’s very clear that you want to avoid listeria; it can cause miscarriage and stillbirth, and pregnant women are especially susceptible.
What is less clear is how to avoid it. Listeria is rare, which is reassuring, but it’s also hard to avoid. Outbreaks crop up at random—in the last couple of years there were large outbreaks in cantaloupe and celery, for example. If you took what would seem like an obvious approach—avoid everything that has caused known outbreaks in the last 10 years, say—you would put deli turkey on your list, but also bean sprouts, chicken, celery, and cantaloupe.
You can certainly avoid all of these foods, although you don’t know if listeria will crop up next in something else. Another approach is to avoid the foods that contribute to a large share of infections. That list would be pretty short: between 2009 and 2011, raw milk cheese caused 50 percent of outbreaks with known cause, and no other source accounted for more than one outbreak.
There has been one outbreak in the past 15 years due to ham (the closest outbreak source to soppressata). With those numbers, I would get the sandwich.
I'm about halfway through my pregnancy and wondering about sleeping while pregnant: Does it really matter how I sleep? I often wake up on my back or even (more regularly) on my stomach. Do I need to barricade myself into sleeping on my left side only? Can I squish the baby when I roll onto my stomach?
First, let me assure you that you will not squish the baby on your stomach. If you’re halfway through your pregnancy, you probably do not have a lot of stomach-sleeping left, so enjoy it while you can.
Back sleeping gets more of the negative press. The theory is that as the uterus get larger (beyond 20 weeks or so), it can compress an important blood vessel when you are lying on your back. If this decreases mom’s blood pressure, it could reduce blood flow to the placenta and baby. This worry stems from the fact that some women feel faint when lying on their backs during pregnancy. What is the more relevant question for you is whether there is any evidence that this actually has risks for the baby. If you wake up on your back, should you worry?
The answer, not especially helpfully, is probably not.
In one very good study, researchers had pregnant women lie on their backs, and they measured blood pressure and the blood flow to the uterus. They found that lying down has no particularly bad impact on blood flow. A couple of women in that study became uncomfortable but felt better when they changed positions. The authors conclude that some women might be uncomfortable sleeping on their backs, but if you are not one of them, you should feel fine about it.
This paper was included as part of a review article about the topic, which ended by saying that pregnant women should be encouraged to sleep in any position they find comfortable.
I say “probably” in my answer above because last year a new study came out that did show a link between maternal sleep position and stillbirth. The researchers interviewed women who had recently had a stillbirth and found that relative to similar women who had healthy babies, the women who had stillbirths were more likely to have slept on their backs. This study wasn’t perfect—it’s small and the researchers were looking at a lot of outcomes, not just stillbirth—but the effects were statistically significant and large (back-sleeping doubled the risk of stillbirth).
So we're left in a frustrating but common position: More research is needed. In the interim, it's not clear what the right conclusion is. Sleeping on your left side, which is encouraged because it does not risk artery compression, is unlikely to be bad, so that's a good option if you can manage to get some rest that way.