I’m no stranger to pregnancy cravings. When I was pregnant with my son, all I wanted were peanut butter and oranges. With my daughter, I thought about Cobb salads morning, noon, and night.
Food cravings are a well-known and common companion of pregnancy. Indeed, somewhere between 60 to 80 percent of moms-to-be say they have a distinct urge for certain foods while gestating their little ones. Why is this? What causes pregnant women to yearn for pickles and ice cream or be overcome by the immediate need for a tuna fish sandwich? And how should you respond — do you succumb to your cravings and let your impulses guide your diet?
Cravings haven’t been the focus of many rigorous studies, but some researchers have discovered interesting trends when it comes to pregnant women and food preferences. Nutrition scientists at the University of Connecticut found that, depending on the trimester of pregnancy, moms taste certain flavors more intensely and either prefer or dislike them. In the first trimester, for example, moms in their study found bitter tastes especially potent and aversive. Evolution likely shaped a mom’s perception of bitter flavors this way, so that she would be leery of strong-tasting plants or spoiled foods, which are more likely to contain a toxin that could hurt the baby. Early on, this could be why some moms who formerly love such treats turn up their noses at coffee, alcohol, or spicy foods. As pregnancy progresses (and the baby’s critical organ formation completes), moms tend not to feel sick at the thought or smell of pungent foods anymore.
The same study found that a mom’s perception of salty and sweet flavors can change as well. In the first trimester, moms tasted salty foods more intensely but preferred this flavor more as they approached the second and third trimester (bring on the potato chips!).
Citric acid (a sour taste) preference also increased through pregnancy so that moms were more inclined to eat sour foods as the due date drew near. No one knows exactly why this is, but the researchers wonder whether the increased desire for salty or sour foods encourages a varied diet, which sends baby a range of nutrients (this could be why some moms crave strange combinations of foods). A hankering for salty foods, like pickles, could also indicate the need for more sodium that comes with a mom’s increase in blood volume during pregnancy.
It’s important to note that genes also play a role here, because DNA partly determines how our taste buds register flavors and our brains perceive them. For example, people respond to bitterness differently based on whether they have a particular variation of genes that shape taste receptors for this flavor. So whether or not you’re pregnant, being turned off completely by broccoli but drawn to the creamy sweetness of yogurt depends, in part, on your genetics.
There’s no doubt hormone fluctuations can also cause cravings (hence a strong pull toward a pint of chocolate ice cream during certain times of the menstrual cycle). And one study of college students found that 97 percent of women but only 86 percent of men reported food cravings. It could be that it’s more socially acceptable for women to shout out their burning desire for fries and a root beer float, but the fact that women are much more likely to have cravings suggests a physiological component. When we’re feeling the fatigue of pregnancy or overwhelmed by our growing bellies, changing lives, and responsibilities, some foods simply make us feel better. For example, carbohydrates and foods containing tryptophan could give a boost to the mood-regulating neurochemical serotonin. We also know that being sleepless — which comes with the pregnancy territory — makes us more likely to crave fatty foods.
But whether or not cravings have a biological basis, any food that makes us feel good once is likely to call out to us over and over throughout pregnancy — that’s a simple Pavlovian fact. For me, once I indulged in my Cobb salad’s blue cheese (salt) and bacon (fat), I couldn’t get that food out of my head. Evolution might have set me up with heightened tasting skills during pregnancy, but once I gave in, just the idea of Cobb salad caused me to salivate. And in fact, psychologists say that mental imagery is an important component of any food craving. If you tend to picture a food clearly in your mind (rather than just having the loose thought that it sounds yummy), you’re going to have a strong craving for it. Can you see the jar of peanut butter or the gallon of Ben and Jerry’s? Then you may be powerless against it.
The fact that moms are drawn to (or repulsed from) certain flavors throughout pregnancy suggests that we should listen to our cravings, because they indicate a need for particular nutrients. The evidence for this isn’t great, though. And if it is true, the everything-in-moderation stance is probably still best. Remember that humans didn’t evolve with Twinkies at our fingertips, so our dietary impulses aren’t very smart guides in the modern world. Pregnant or not, most of us (myself included) would gravitate toward non-stop croissants and BLTs if we went by this principle. Better to keep a healthy diet during pregnancy, indulge here and there, and try to enjoy the unique tastes that come with this very special time.