For most women, morning sickness during pregnancy is simply part of the baby-making process, like choosing the perfect name and preparing that beautiful nursery, and yet scientists have only recently been able to identify the possible cause.
There are many misconceptions surrounding the annoying morning sickness that pregnant women experience. Some dismiss it as ‘hormonal’, while others believe it randomly chooses expectant mothers. An important new UCLA study However, has shattered these views and revealed that this difficult aspect of being pregnant may in fact be a useful and natural immune response.
According to the National Institute of Health, up to 80% of pregnant mothers experience some form of nausea during the early stages, leading to vomiting and strong aversions to specific foods and smells. Experts now suggest that despite the feared symptoms, this phenomenon has actually evolved to protect baby and mother. “During pregnancy, a mother’s immune system faces a difficult challenge,” explains UCLA anthropology professor Molly Foxwho served as corresponding author on the groundbreaking study. “It must 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. Normally the immune system attacks anything that seems foreign, so during pregnancy it must carefully adapt to keep the fetus safe while still defending itself against infection.”
How was the research conducted?
The UCLA-led team analyzed blood samples from 58 Latina women in Southern California, who were observed from early pregnancy through postpartum. One of the main purposes of the study was to measure immune system molecules called ‘cytokines’. These are proteins that send signals to help the body mount a rapid defense against disease while regulating inflammation. Participants were also asked to complete questionnaires asking about their symptoms related to morning sickness, along with their aversions to eating and smelling during the early stages of pregnancy.
What were the results?
Once collected, the data showed that 64% of study participants experienced odor or food aversions, with the main triggers being tobacco smoke and meat. The women who experienced an aversion to tobacco smoke also showed an increased inflammatory response. This correlation is consistent with the researchers’ theory: that these symptoms may be part of an evolutionary adaptation that helps pregnant mothers’ bodies minimize their exposure to harmful substances.
UCLA warns that the evidence is not yet definitive and more research is needed on a larger sample size to confirm their results, but why do humans suffer from morning sickness when other mammals quit Scot-Free? “In many mammals, the fetal compartment has barriers that separate it from the mother’s blood supply, where her immune cells are located,” Fox explains. “But in humans we have a unique setup: fetal cells are bathed in maternal blood. Humans have the most invasive of all placentas, which burrow deep into maternal tissue. So humans need unique strategies to prevent the mother’s immune system from attacking the fetus.”
These immunological changes can cause nausea, which in turn encourages food avoidance as a potential extra layer of protection. “Nowadays you see labels on packages of ground beef or soft cheese warning pregnant women to be careful with these products due to the risks of foodborne illness during pregnancy,” notes Professor Daniel Fessler, who also co-authored the new study. “Aversions to certain smells and foods, and nausea and even vomiting, appear to be evolution’s way of achieving that same goal.”
The researchers hope that information from this study can help strengthen recognition that nausea and vomiting are normal symptoms with a biological basis linked to healthy pregnancies, while the results can help pave the way for common sense workplace adjustments, keeping pregnant mothers away from morning sickness triggers whenever possible.
#UCLA #study #suggests #morning #sickness #evolved #immune #response #hormones