Pickles and ice cream. Chicken nuggets dipped in chocolate syrup. Mashed potatoes slathered in butter and Tabasco sauce. And plain old dirt.
Pregnancy cravings can be funny, a little gross sounding, or just plain weird, but you might wonder: is there a biological cause that helps explain why a pregnant woman might find herself craving strawberries dipped in peanut butter?
Science has not pinpointed the driving force behind cravings, though there are theories. Pregnancy cravings are well known, even as far back as the ancient Greeks. A famous Greek physician named Soranus wrote in his seminal work, Gynecology, that pregnancy included a stage involving “appetite for things not customary.” This appetite extended to nonfood objects, such as dirt.
Although a definitive cause has not been established for cravings, scientists have found that during pregnancy women become somewhat resistant to a hormone called leptin, an endocrine growth factor. Leptin is responsible for reducing appetite.
Without this appetite-suppressing hormone, the appetite receptors in the brain are free to be stimulated by a chemical neurotransmitter in the brain (called neuropeptide Y) that’s involved in many bodily reactions, such as stress, excitability, and hunger.
Pregnancy also seems to change a woman’s sensitivity to odor. More than 75 percent of pregnant women say they experienced altered smell and taste perception at some point in their pregnancy. Scientists theorize that as the uterus expands, neurons nearby may interact with one another, causing the heightened sense of smell and taste. In turn, this heightened sense can affect cravings.
But the question still remains: Why dirt? Or even stranger: Why laundry starch? Or toothpaste?
This craving of non-food items (including those listed above) is called pica. Some theories as to what causes pica include a connection to iron deficiency or the body’s attempt to consume missing vitamins or minerals. If you find yourself eating or wanting to eat these substances, be sure to let your provider know so your blood count and iron stores can be checked.
Overall, indulging a craving here or there is not harmful. It does become a problem, however, if you are making daily midnight trips to the drive-through for French fries. Keep in mind that women carrying one baby only need 300 calories more/day, so be sure your cravings aren’t pushing you well over this limit.
Reviewed by Dr. Jen Lincoln, November 2018
- Cravings are common in pregnancy.
- Changes in the sensitivity to certain hormones can alter a pregnant woman’s appetite.
- Pica is the craving of non-food items, and may signal anemia.
- It is OK to occasionally indulge cravings, but they should not drive your whole diet.