Final answer:
The nurse's primary intervention for poor maternal nutrition during pregnancy is to initiate nutritional counseling, ensuring the necessary nutrient intake for fetal development.
Step-by-step explanation:
The nurse's primary intervention for a pregnant woman with poor nutrition or inappropriate ingestions would be to initiate nutritional counseling. This intervention directly addresses the issue by providing the mother with information and guidance on how to improve her diet to ensure adequate intake of essential nutrients for both her own health and the developing fetus's growth. During pregnancy, the mother needs extra calories, proteins, and lipids, as well as vitamins and minerals such as folic acid, calcium, iron, and omega-3 fatty acids to support fetal development. Therefore, nutritional counseling is crucial to help the mother understand the importance of nutrition and how to meet these increased demands.