Cravings and Aversions
Pregnancy is notorious for inducing cravings and aversions in women, the reasons for which still allude scientists. Researchers theorize cravings and aversions could be the result of hormonal changes, nutrient deficiencies, a change in women’s sense of smell, stress, or nausea. These factors can cause a woman to both crave and avoid certain items.
While none of these theories have strong evidence to support them, there is also no major medical concerns or complications that result from cravings and/or aversions except for the possibility of excessive weight gain or the development of pica.
Pica is the practice of craving nonfood items with little or no nutritional value, as well as substances that can potentially be harmful.
Women who are craving items such as clay, chalk, paper, cornstarch, and/or ice should contact their HCP immediately as pica can cause life-threatening complications depending on the substance consumed. Further, it is also possible pica is the result of an underlying medical concern that needs to be identified and treated.
Background
Cravings are very strong urges for food items that are more intense and difficult to ignore than simply being hungry and trying to figure out what to eat.
Cravings are common in pregnant women all over the world, but based on food availability and cultural aspects, specific food items craved are very different. Chocolate has consistently been found to be the most craved food in the United States during pregnancy and menstruation.
Additional commonly craved items include sweets, ice cream, candy, starchy carbohydrates, fruits, vegetables, fast food, pickles, and pizza. Cravings for items that are salty/savory are not reported as often.
Causes
In general, cravings are not well studied, understood, or easily explained; but due to strong anecdotal evidence of this occurring during both pregnancy and mensuration, researchers believe hormones likely play a role.
However, there is no strong evidence that women experience cravings during either event that correlates to hormone levels; therefore more research is necessary to fully explain this symptom.
However, regarding sense of smell, there is no empirical evidence that pregnant women generally identify odors consistently better than non-pregnant women, despite the overwhelming prevalence of this symptom
It has also been hypothesized that cravings could be caused by a deficiency in certain nutrients and therefore a pregnant woman craves that item in order to obtain that nutrient. However, it is very unlikely commonly craved food items during pregnancy such as sweets, pickles, fast food, and chocolate satisfy any nutritional deficit, which is why this hypothesis has recently lost favor.
Additionally, since the fetus needs more nutrition and women need more calories as pregnancy progresses, cravings should follow this same trajectory, but cravings actually tend to decrease as pregnancy progresses.
Since the most commonly craved food items are starchy high-fat substances, and appear in the first trimester, another hypothesis is that cravings are meant to help alleviate nausea and vomiting (NVP), gain quick energy, and protect the mother from potential toxins in other items (vegetables, meat). However, this hypothesis is also controversial.
Researchers have also theorized culture could be the main driver of cravings. In Western culture, pregnancy is a socially acceptable time for women to consume certain foods that are otherwise “taboo” without feeling judged, and in some cases, these eating habits are encouraged. Pregnant women could crave these items as a relief from stress, or a break from more stricter calorie control and enjoy them while it is culturally considered acceptable to do so.
Pica is the compulsive eating of material that may or may not be food and has been formally documented since the 16th century. The prevalence of this condition is difficult to estimate due to varying definitions of pica and the reluctance of individuals to report cravings of nonfood items.
The most common substances craved and/or consumed by women with pica include soil, ice, cornstarch, uncooked rice, chalk, baby powder, soap, baking soda, sponges, burnt matches, charcoal, cigarette ash, and paper.
Pica is thought to be a manifestation of an underlying medical condition, most likely due to malnutrition, or a deficiency in a specific nutrient; research remains inconsistent however, especially regarding iron and anemia.
Pica and iron deficiency are commonly associated, and studies indicate that anemia (caused by iron deficiency) can result in pica but the reasons for this are not clear. However, pica can also cause anemia, therefore more research is needed regarding nutritional deficiencies and the development of pica.
Craving ice is also commonly reported to be a symptom of iron deficiency and pica, and cravings for ice are usually resolved when iron supplementation is started.
Interestingly, since ice contains no iron, it is theorized that chewing ice creates a vasoconstrictive response that provides faster blood flow to the brain. This results in increased alertness that may counteract mental deficits created by iron deficiency.
Despite a lack of general understanding of the causes of pica, pica is dangerous and can cause gastrointestinal complications especially when nonfood items are consumed.
The most common complications include constipation, bowel obstruction, and perforation. Additional complications depend largely on the item consumed, but can include heavy metal poisoning, malnutrition, consumption of bacteria and parasites, and mercury poisoning, as well as an excess or deficiency of potassium. Many of these complications are potentially life-threatening.
It is strongly advised that women who crave nonfood items call their HCP for evaluation.
Aversions
Women may also have strong aversions during pregnancy, mostly in the first trimester, which some researchers associate as a causal factor of NVP.
Women should identify these aversions early and let other household members know what they are; this can help them avoid unnecessary and unexpected nausea and/or gagging.
Although the cause of aversions in general during pregnancy is not known, it has been documented for more than 100 years that pregnant women have a heightened sense of smell – known as hyperosmia.
However, recent research indicates this is more likely a heightened awareness of certain smells, rather than a “better” sense of smell than non-pregnant individuals.
This hyperawareness appears to only include specific odors – usually intense, harmful ones. Pregnant women may be better aware of odors that are less pleasant or potentially harmful and then pay more attention to them.
For example, when women are already aware that cigarette smoke, coffee, garbage, and spoiled food are associated with harm during pregnancy, their odors may become “stronger" (read more).
Action
Women should feel free to indulge in cravings during pregnancy. Current evidence indicates that moderation is the key to longer-weight control success rather than complete restriction of favorite foods (read Nutrition Introduction for more information).
Women can struggle with aversions during pregnancy, especially in the first trimester, which can worsen (or cause) nausea and vomiting. Women who wish to learn more about the management of aversions while experiencing NVP can read more here.
Women who experience strong cravings for items that are not considered "food" need to call their HCP immediately. Women should not feel judged, ashamed, or fearful to report these symptoms to their HCP. Women can also share/email this page to their HCP as a talking point, so the HCP can bring it up first.
Women should also consider sharing and submitting their experience below regarding their cravings and aversions during pregnancy, to include tips on how to overcome or avoid certain aversions.
Resources
Nutrition during Pregnancy (American College of Obstetricians and Gynecologists)
Pica – Clinical Methods (NCBI Online)