Smell That Again?: Does Being Pregnant Heighten Your Sense of Smell?

Posted on March 6th, 2020 by

Written by Kristine Falness, Emee Jagielski, Amber Forrester, and Yumiko Yoshioka

Imagine this: You or someone you know has just found out that they are pregnant with their first child and have recently been noticing changes in their sense of smell. They do not know what could be causing these changes, so they decide to test the smells around them. Everyday food and products that are part of their daily routine are beginning to bother them. They start to eliminate these products one by one throughout their pregnancy. Nothing helps. This makes you wonder why these scents are affecting those who are pregnant now and not before they became pregnant.

It has been hypothesized that a heightened sense of smell within pregnant women can be a trigger for nausea and vomiting (Heinrichs, 2002). This heightened sense of smell simply means an increase in sensitivity and recognition of odors, which typically occurs during the first trimester of pregnancy (Cameron, 2014). However, there is conflicting evidence on what specifically causes these phenomena in women during that time. Therefore, research on this subject focuses on the underlying mechanisms that could possibly cause this olfactory change. A few of those mechanisms include hormones such as estrogen, a condition called hyperosmia, and or the theory of hedonism.

One of the mechanisms that tends to take most of the blame for this keener sense of smell during pregnancy, is a hormone called estrogen. According to the University of Rochester Medical Center (“Estrogen’s Effects,” n.d.), estrogen plays an important role in women’s sexual and reproductive development. The ovaries, which produce a woman’s eggs, are the main source of estrogen in a woman’s body. Small amounts of this hormone are also produced in the adrenal glands as well as fat tissue, this allows estrogen to move through blood and act everywhere in a woman’s body. According to Dr. Leslie Cameron (2014) from the Department of Psychological Science at Carthage College, “Estrogen levels rise throughout pregnancy, reaching their peak shortly before parturition. Thus, one would predict that smell function should improve across pregnancy if estrogen, alone, were involved.” Nevertheless, she notes that no studies have ever been done to measure hormone levels and smell function simultaneously during pregnancy, therefore the evidence so far does not suggest a strong correlation between estrogen. With estrogen being an unlikely cause for this change in pregnant women, a condition called hyperosmia may then be to blame.

Let’s imagine you are in a floral shop trying to decide what kind of flowers you want to buy. You’ve noticed in your past experiences here that the odors given off from all the different types of flowers meshed together, making it difficult to distinguish one type from another. Only up until now when you are pregnant, you are able to smell strong distinctions between each flower type, making you more inclined to purchase one solely based on its odor. You smell several types of flowers including a rose, lily, and lavender. At this time, your sense of smell is stronger for the lilies than any other flower, and you decide to buy it. Why does this happen? This symptom may be explained by hyperosmia. Hyperosmia refers to the condition in which there is an increase in olfactory sensitivity. Steiner (1922) reported that almost all pregnant women experience a stronger sense of smell, usually in the early months of pregnancy and particularly in a women’s first pregnancy. Particular odors such as cigarettes, perfumes, spoiled food, spices, and coffee were reported to make those who were pregnant more abnormally sensitive when it came to their olfactory system (Nordin et al, 2014). However, several studies have found that there is no significant difference in olfactory detection thresholds, the level of strength a stimulus must reach to be detected, between non-pregnant women and women in the first trimester of pregnancy (Cameron, 2014). In addition, other researchers revealed sensitivity during late pregnancy is lower than normal (Gilbert & Wysocki, 1991) and reported anosmia in pregnancy, which is an experience of distortions in the perception of particular odors (Nordin, Broman, & Wulff, 2005). For that reason, it is still unclear if all women during pregnancy experience this change of smell, as did you when having a stronger sense of smell for the lilies than any other flower.

Why did you like the smell of the lilies in particular? You usually don’t have a preference for odor when buying flowers, but at this specific moment you experienced the odor of the lilies as more pleasant than any of the other flowers. Odor hedonics, which is perceiving a stimuli as pleasant or unpleasant, may be another possible reason for this hypersensitivity of smell. According to Cameron (2014), there is a tendency for pregnant women to rate some odors as pleasant and the others as less pleasant. Gilbert & Wysocki (1991) reported fluctuating results that some odor intensity differs among pregnant women. For example, their study has shown that pregnant women were more likely to experience odors (e.g. orange, grape, natural gas) as less pleasant than non-pregnant women. Thus, pregnancy may affect the perception of some odors but not all because most pregnant women could specify particular odors that they found more or less pleasant. Perhaps the effect of pregnancy on olfaction is not significant based on these studies. Therefore, it is still unknown as to why the smell of the lilies was increasingly more pleasant to you than any other flower you smelled at that moment in time.

With this being said, there isn’t enough research done to produce a definite answer as to why women experience a heightened sense of smell during pregnancy. Though there is no treatment for this, here are some strategies for those who are pregnant to try and eliminate the symptoms; eat smart, keep clean, freshen up, ditch fragrances, and sniff the good stuff that actually makes you feel better (O’Connor, 2019). For those who are around pregnant women, try to be considerate to their sensitivities as it affects them being around others and the odors those individuals emit. Hopefully by trying these tips, you or the person experiencing these symptoms can be more comfortable for the remaining duration of their pregnancy.


Cameron E. L. (2007). Measures of human olfactory perception during pregnancy. Chem. Senses 32 775–782 10.1093/chemse/bjm045

Cameron, E.L. (2014) Pregnancy and olfaction: a review. Front. Psychol. 5:67. doi: 10.3389/fpsyg.2014.00067

Estrogen’s Effects on the Female Body. (n.d.). Retrieved from

Gilbert, A. N., & Wysocki, C. J. (1991). Quantitative assessment of olfactory experience during pregnancy. Psychosomatic Medicine, 53(6), 693–700. doi: 10.1097/00006842-199111000-00009

Heinrichs L. (2002). Linking olfaction with nausea and vomiting of pregnancy, recurrent
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Nordin S., Broman D. A., Olofsson J. K., Wulff M. (2004). A longitudinal descriptive study of self-reported abnormal smell and taste perception in pregnant women. Chem. Senses 29 391–402 10.1093/chemse/bjh040

Nordin, S., Broman, D., & Wulff, M. (2005). Environmental odor intolerance in pregnant
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O’Connor, A. (2019, May 2). Heightened Sense of Smell During Pregnancy. Retrieved from

Steiner, G. (1922). Psychische Untersuchungen an Schwangeren. Archiv Für Psychiatrie Und Nervenkrankheiten, 65(1), 171–190. doi: 10.1007/bf02029573


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