Hunger
Women can feel much hungrier throughout the entirety of pregnancy, with “peak hunger” occurring in the late first trimester to the second trimester.
Hormones play a significant role in appetite regulation during early pregnancy, and since appetite-inducing hormones are also released by the placenta and the fetus, it is evident that proper fetal growth and development may require a surge in these hormones to ensure adequate food intake.
A pregnant woman’s body also goes through dramatic physical changes to prepare for pregnancy, such as increased cardiac and metabolic demands which lead to fatigue and exhaustion, and therefore a desire to consume more food.
Further, pregnant women also famously experience cravings. Although the causes of specific cravings during pregnancy are not known, increased hunger could lead to strong desires for certain foods.
Therefore, hunger, together with cravings, may serve a purpose during pregnancy; women should aim for as much nutrition as possible with every meal, remain physically active, stay properly hydrated, and indulge in cravings in moderation.
Women should talk to their HCP if they have any questions or concerns regarding their appetite during pregnancy.
Background
Women frequently report feeling hungrier and eating more during pregnancy than prior to pregnancy. Hormonal influences, higher metabolic demands on the body, cardiac changes, fatigue, extra nutrient needs, and an increased requirement for oxygen can all cause increased hunger during pregnancy.
By the third trimester, a woman’s basal metabolic rate rises by 20% compared with non-pregnant women. It is estimated, on average, the total gestational period of pregnancy may require an additional 77,000 calories at 85, 285, and 475 extra calories needed per day during the first, second, and third trimesters, respectively.
Hormones
Hormones also play a strong role in increased hunger, especially early in pregnancy. Pregnant women begin feeling hungrier almost immediately, well before significant increased demands are placed on the body.
The early production of human placental lactogen (hPL) and progesterone increases the appetite of a pregnant woman; both hormones are well-known appetite stimulants (estrogen decreases appetite).
Leptin is a hormone produced by fat cells. In non-pregnant individuals, leptin acts in the hypothalamus (the control center for hunger and satiety) to suppress appetite and food intake. Interestingly, the opposite occurs during pregnancy. Leptin concentrations are increased, and the body appears to be in a state of leptin-resistance.
Further, the placenta, mammary glands, and certain fetal organs such as heart, bone, cartilage, and possibly the brain, all produce leptin. This is hypothesized to occur to help regulate fetal growth and development and make sure the woman consumes enough food for both (or more) of them.
Pregnancy also causes an increase in the production of thyroid hormone from 50% to 100% of pre-pregnancy levels, which raises the maternal metabolic rate. This can significantly increase a pregnant woman’s appetite.
Ghrelin, known as the “hunger hormone”, is produced and released into the bloodstream mainly by the stomach. It stimulates appetite, increases food intake, promotes fat storage, and plays a role in the control of insulin release, all important variables during pregnancy.
When extra ghrelin is given to humans, food intake increases. Levels of ghrelin increase right before eating and when someone has not eaten in some time (results in “hunger pains”). Ghrelin also increases when an individual changes or limits their diet, which is one of the reasons weight loss is so difficult.
Conversely, eating reduces concentrations of ghrelin, and different nutrients can slow down ghrelin release to varying degrees, which is why different food groups with different levels of carbohydrates, proteins, and fats, can affect appetite differently.
Although not much is known about ghrelin’s role during pregnancy, it is thought to somehow regulate appetite and energy requirements. Ghrelin and its receptors have been identified in the placenta, clearly indicating a role for ghrelin in reproduction.
Ghrelin concentration begins to increase right away in the first trimester, reaches the highest level at mid-pregnancy, and reduces to the lowest level in the third trimester and after delivery.
Cravings
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.
Researchers theorize cravings could be the result of hormones, nutrient deficiencies, a change in women’s sense of smell, stress, quick energy, nausea relief, or even cultural acceptance.
Regardless, women's experiences with cravings plus increased hunger could be the result of the body attempting to consume enough energy – especially quick energy – during pregnancy (read Cravings and Aversions).
Action
It is recommended all pregnant women eat a balanced diet rich in fruits and vegetables, high-quality carbohydrates, and a variable mix of proteins from beans, lean meats, fish, and seafood (for amino acids). Diets should also be limited with added sugar, red meat, and processed foods.
However, women are also encouraged to consume a diet of moderation – to include cravings and “unhealthy” items. Women may find it harder to stick to a healthier diet overall if they completely eliminate their favorite foods.
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 (read Cravings and Aversions).
Lastly, if women are concerned at any time they may be gaining too much weight, or have questions regarding their nutrition or appetite, they should talk to their HCP.
Women should also consider sharing and submitting their experience below regarding their appetite during pregnancy.
Resources
Nutrition During Pregnancy (American College of Obstetricians and Gynecologists)