Morning sickness symptoms, including nausea, vomiting and aversions to certain foods and smells, are linked to the body’s complex natural immune response during pregnancy, according to a UCLA study released Thursday.
In the early stages of pregnancy, a mix of inflammatory responses and behavioral mechanisms that researchers believe are adaptive, such as nausea, achieves a delicate balance, allowing the mother to tolerate and nourish the fetus while also avoiding potentially harmful foods, according to UCLA researchers.
The study could have workplace implications for pregnant women, helping to widen recognition that the symptoms are healthy and normal, both reducing stigma and paving the way for common-sense workplace accommodations, according to the university.
According to the National Institutes of Health, as many as 80% of women in the early stages of pregnancy experience some types of morning sickness, such as nausea, vomiting and aversions to certain foods and smells. The symptoms can be uncomfortable, but they are not typically a sign that anything is wrong with the health of the mother or the developing fetus, but rather an indication of a delicate balance unique to pregnant women, according to the NIH.
“During pregnancy, a mother’s immune system faces a tricky challenge: it has to protect both her and the fetus from infection, but without accidentally attacking the fetus, whose genetic identity is half-foreign because it is half derived from the father,” UCLA anthropology professor Molly Fox said in a statement. “Normally, the immune system attacks anything that seems foreign, so in pregnancy, it has to carefully adjust to keep the fetus safe while still defending against infection.”
UCLA researchers said that balance of protecting both mother and fetus is achieved by a mix of inflammatory responses. Those responses prevent the mother’s body from rejecting the fetus, while symptoms such as nausea encourage the mother to avoid foods that are potentially harmful, especially in the first and second trimesters when the fetus is most vulnerable.
For the study, the UCLA-led team of anthropologists and epidemiologists collected and analyzed blood samples to measure immune system molecules called cytokines. Cytokines are proteins that send signals to help the body launch a quick defense against sickness and regulate inflammation.
Participants also completed questionnaires that asked about morning sickness-related symptoms and food and smell aversions during the early stages of pregnancy. The participants were 58 Latina women in Southern California who were followed beginning in early pregnancy through the postpartum.