The consumption of dairy products during pregnancy provides much needed nutrients (calcium, Vitamin D, protein) and is strongly linked to healthier fetal growth, development, and birth weight.
Further, regular consumption could help prevent dairy/lactose allergies in infants/children, but this research is considered preliminary and remains controversial.
While dairy can be considered a healthy part of the diet during pregnancy, moderation is key. Women should avoid high and regular consumption of full fat dairy products when possible to prevent a higher than recommended weight gain (some weight gain is necessary). Lower-fat dairy products can be consumed more regularly, but women need to monitor these products for added sugars (i.e. yogurt).
If women cannot eat or tolerate dairy, and are concerned about their calcium or vitamin D intake, they should talk with their health care provider (HCP). However, green leafy vegetables, almonds, broccoli, chickpeas, spinach, and fortified foods and juices are also good sources of calcium and other valuable nutrients during pregnancy.
Background
Dairy products contribute several essential nutrients to the diet, with high concentrations of protein, calcium, phosphorus, potassium, iodine, vitamin B12, vitamin D, and riboflavin (B2).
Calcium is the most recognized nutrient provided by dairy products. Calcium intake is especially critical during pregnancy and lactation because of the potential negative effects on maternal bone health if a woman does not obtain enough calcium either before or during pregnancy.
Pregnancy
Further, HCPs generally recommend increased servings of milk and dairy products to meet requirements of the above nutrients. (Some fortified soy milks now contain equal amounts of protein, calcium and vitamin D.)
In addition, numerous worldwide studies report positive associations between milk and/or dairy consumption and fetal growth, placental weight, and birth weight.
A higher intake of yogurt and milk has also been associated with a lower prevalence of depressive symptoms during pregnancy, although the mechanism for how this occurs is not known.
Preliminary research indicates It is also possible that a high consumption of milk products during pregnancy can lower the risk of cow's milk allergy in children, but more research is needed. Further, the mechanisms for how a mother's consumption of certain foods can affect infant/childhood allergies is still being studied.
The calcium provided through consumption of dairy products has also been linked to stronger teeth in children, as a child's "baby" and permanent teeth develop in utero (during pregnancy). In contrast, other studies indicate that neither calcium nor fluoride supplementation in the mother is necessary for this outcome as long as children have access to fluoridated dental products (toothpaste) when their teeth come in.
As important as the above factors are, additional dairy intake through full-fat milk, cheese, and yogurt can also add hundreds of additional calories if the diet is not adjusted, and may increase the risk of a large-for-gestational age baby. However, reduced-fat milk and dairy products may lessen weight gain while still providing the mother and fetus with valuable nutrients.
Note: While dairy products can contain varying levels of hormones such as estrogen, progesterone, and prostaglandins, and could theoretically alter female reproductive function, there is currently not enough evidence to explain what those effects might be (especially during pregnancy), the hormones responsible, the dairy products most at risk, or the minimal amount at which negative effects may start to appear. Hormones in dairy milk and their possible affects on human pregnancy has not been studied.
Food Sources
Reduced-fat milk, cheese, yogurt (aim for low sugar), and ricotta cheese are good dairy sources of calcium, and some fortified products contain several other vitamins and minerals.
Pregnant women need to be cautious of purchasing raw milk and other raw dairy products, which is legal in many states. Raw milk and milk products from cows, goats, and sheep are a source of bacterial infections caused by pathogens such as listeria, E. coli, and salmonella, as well as others.
Researchers have noted that the benefits attributed to raw milk have not been shown in evidence-based studies, and therefore, the risk of infection and serious illness from these products is larger than any potential or perceived benefit of raw milk.
Interestingly, the ability to digest lactose may improve during pregnancy for some women, especially later in pregnancy. Pregnant women may be able to drink milk and eat other dairy products without discomfort as they progress through pregnancy (specific to intolerance only, not allergies).
Note: Non-dairy sources of calcium include kale and other leafy greens, canned seafood, soy beans and other soy products, broccoli, and fortified cereals, breads, and juices.
Action
While lower-fat dairy products can help women obtain essential nutrients, women should be mindful of the added sugar in most of these products (i.e. yogurt). Full fat dairy products can also be a part of a healthy diet during pregnancy, as long as these are consumed in moderation.
Pregnant women who are concerned about their calcium or vitamin D intake during pregnancy, or those who do not eat dairy, can speak to their HCP about making sure they obtain these nutrients from other aspects of their diet. In some cases, supplementation may be required.
Resources
All About the Dairy Group (ChooseMyPlate.gov)