When a person is pregnant, the body requires a consistent supply of energy and nutrients to support both their own physiological functions and the rapid development of the growing fetus. The phrase “not eating” refers to a significant and sustained period of inadequate caloric intake or severe nutrient deprivation. This situation can arise from food insecurity, restrictive dieting, or complications like severe nausea and vomiting (Hyperemesis Gravidarum). Because a balanced diet provides the foundational building blocks for a healthy pregnancy, any prolonged nutritional shortfall can trigger adverse effects on both the pregnant person and the developing child. These consequences range from immediate physical strain on the mother to long-term implications for the baby’s growth and organ function.
Maternal Physical Strain
When caloric intake is severely reduced, the pregnant person’s body enters a catabolic state, breaking down its own tissues for energy. This process causes hypoglycemia, a drop in blood sugar, as the body struggles to maintain glucose levels for itself and the fetus. The body instinctively prioritizes nutrient transfer to the developing baby through the placenta, often at the expense of maternal stores.
This maternal nutrient depletion leads to chronic fatigue and muscle wasting as protein is broken down for energy. If micronutrient intake is insufficient, the body pulls reserves from its own tissues, such as drawing calcium from the bones to meet the fetus’s skeletal needs. The breakdown of fats into ketones results in ketosis, which indicates a severe nutritional deficit.
Impact on Fetal Growth and Size
A sustained lack of energy and macronutrients directly affects the physical accumulation of mass in the developing fetus. The most common outcome of inadequate maternal nutrition is Intrauterine Growth Restriction (IUGR). IUGR describes a condition where the fetus is unable to achieve its genetically determined growth potential, often resulting in a size below the tenth percentile for gestational age.
Infants affected by IUGR are frequently born with low birth weight (LBW), defined as weighing less than 2,500 grams (5 pounds, 8 ounces) at birth. Severe maternal malnutrition is also associated with an increased likelihood of preterm birth, or delivery before 37 weeks of gestation. Both LBW and prematurity complicate the infant’s transition to life outside the womb and are linked to higher rates of infant morbidity.
Consequences for Organ and Neurological Development
Beyond simple size, inadequate nutrition during specific developmental windows can permanently compromise the function and structure of organs. The first trimester is a period of rapid organ formation, and nutrient deficiencies during this time can result in structural anomalies. Folic acid, a B vitamin, is a well-known example; its deficiency in early pregnancy significantly increases the risk of neural tube defects (NTDs), such as spina bifida, which involve incomplete development of the brain and spinal cord.
Other micronutrients are equally important for functional development, particularly in the brain. Insufficient intake of iodine, necessary for thyroid hormone production, can impair cognitive development and lead to intellectual disability. Iron deficiency restricts oxygen transport to the fetus, compromising the development of the cardiac and neural systems and potentially resulting in long-term cognitive impairment. Malnutrition can also negatively program the cardiac and renal systems, increasing the child’s susceptibility to chronic diseases later in life.
When Inadequate Intake Requires Medical Intervention
When a pregnant person is unable to maintain adequate intake, such as with severe, persistent vomiting (Hyperemesis Gravidarum or HG), medical intervention is necessary to stabilize both the mother and the fetus. HG is characterized by intractable vomiting that results in significant weight loss, dehydration, and metabolic disturbances. Immediate medical attention is warranted if the pregnant person experiences rapid weight loss, is unable to keep any fluids down for 24 hours, or shows signs of severe dehydration like fainting or dark urine.
Medical care focuses on reversing dehydration and replenishing lost nutrients. This often begins with intravenous (IV) fluid resuscitation, which may include thiamine supplementation to prevent Wernicke encephalopathy. For severe, unmanageable HG, a healthcare provider may initiate medical nutritional support, such as a feeding tube or total parenteral nutrition (TPN) in extreme cases. The fetus is closely monitored with regular ultrasounds and weight tracking to assess growth and development.