Some of my patients reported to me that they lost their sense of smell (hyposmia/anosmia) and taste (hypogeusia/ageusia) every time they became pregnant. They said that every once in a while they would get a whiff of something, but then it would be gone. Yet others often experience heightened senses. There are a few reasons why this can happen.
Instead of becoming almost nauseated by overwhelming smells, women report they lose their sense of smell occasionally. In addition, you can lose your sense of smell from allergies, a genetic predisposition, nasal polyps, and certain drugs like antibiotics, antidepressants, and anti-inflammatory medications. It’s also caused by exposure to toxic chemicals and cocaine abuse. Most women who experience anosmia during pregnancy report that it begins early and generally goes away shortly after giving birth.
In one study published in the Oxford journal Chemical Senses, one hundred nonsmoking women who were pregnant, postpartum, or had never been pregnant before were tested using the University of Pennsylvania Smell Identification Test. In correlation with previous reports, 90% of pregnant women reported that specific odors smelled less pleasant and 60% of the pregnant women reported that some odors smelled more pleasant.
At the end of the study, however, it was found that the scientific evidence for women being more sensitive to odors during pregnancy was limited and inconclusive. Most evidence for heightened smell has been anecdotal and it seems that just as many women also experience hyposmia, or a reduced sense of smell, just as often during pregnancy. Anosmia is still not as common as hyperosmia and hyposmia, but isn’t all that uncommon for women to experience at some point during their pregnancy, even if just for a few weeks.
Heightened sense of smell
Having an increased sense of smell (hyperosmia) is something more often associated with pregnancy is called "hyperosmia". Many pregnant women experience hyperosmia during pregnancy, which is a heightened sense of smell, the opposite of anosmia (absence of smell), or hyposmia (decrease of smell). Changing hormones are the reasons behind this.
COVID-19 and loss of taste and/or smell
With the arrival of COVID-19 infections, many infected people report loss of smell and/or loss of taste among their infectious symptoms. In some people losing smell and/or taste is often the most severe symptom and taste/smell usually comes back after recovering from the virus infection. If you have a loss of taste and/or smell, you should talk immediately to your doctor to make sure it is nothing serious like a COVID-19 infection.
Source: Cameron, L. E. (2007). Measures of human olfactory perception during pregnancy. Chemical Senses, 32(8), 775-782.