Here's another reason to load up on yogurt when you're expecting: A recent study published in the journal BMJ Open found that drinking probiotic milk was linked with a lower risk of preeclampsia (dangerously high blood pressure) as well as a lesser chance of preterm birth—but only if consumed at certain points in pregnancy.
Norwegian and Swedish researchers looked at data gathered from more than 70,000 pregnancies as part of the Norwegian and Child Cohort Study. "We observed an association between probiotic milk intake in early pregnancy and a 21 percent lower risk of preterm delivery, and probiotic milk intake in late pregnancy—the second half—and a 20 percent lower risk of preeclampsia," study author Dr. Mahsa Nordqvist, an OBGYN at Sahlgrenska University Hospital in Sweden, tells Parents.com.
Previous research had already identified the link between probiotics, the "good" bacteria that can live in our intestines, and a reduced risk of these pregnancy complications. But in this study the researchers wanted to figure out when in pregnancy it makes the most difference. "Pregnancy is a time of rapid change, and different exposures can have different effects depending on the time of exposure," Dr. Nordqvist says.
The results were surprising. "The first 'step' of preeclampsia occurs when the placenta starts to build up, so we had actually expected that consumption during early pregnancy would play a bigger role," Dr. Nordqvist says. But the results showed consumption in late pregnancy to be most crucial, suggesting probiotics lower preeclampsia risk by reducing the high blood pressure itself. "This is supported by other studies that show probiotics might have the same effect as medication that lowers blood pressure," Dr. Nordqvist says.
As for preterm birth, Dr. Nordqvist says that probiotics may alter the body's response to infection. "Preterm delivery, especially early preterm delivery, can often be related to infection, which leads to inflammation," she says. It's this inflammation that can cause the body to overreact and go into labor. "Our results suggest that if the inflammatory response can be lowered at an early stage, it can lower the risk of giving birth too early."
What preeclampsia and preterm delivery have in common is that both actually cause inflammation, Dr. Nordqvist says. "Probiotics might be able to reduce the inflammation in the body, and therefore, potentially reduce the risk of conditions like these two," she says.
Should you eat probiotics in pregnancy?
This study only proves a connection, not cause and effect, so more research on how probiotics affect pregnancy complications is needed. But Dr. Nordqvist says it can't hurt to increase your probiotic intake in the hope of potential health benefits. "Consuming probiotics is, to our knowledge, safe throughout pregnancy," she says.
When picking probiotics, supplements have varying amounts and types of live bacteria, which may or may not be able to survive while they sit on the shelves and as they make their way through our intestines. "But probiotic bacteria in commercial milk, including yogurt, have been shown to have a good survivability in the whole gastrointestinal tract," Dr. Nordqvist says, noting that her study included the Scandinavian milk products Biola and Cultura, but not supplements. So, you might try comparable foods that contain probiotics like kefir and other fermented foods, acidophilus milk (milk with probiotics), as well as yogurt.