Promoting optimal nutrition in pregnant and lactating women is crucial for maternal and infant health. This study evaluated their nutritional status and dietary habits, assessing macro and micronutrient intake based on recommendations. A descriptive study with Spanish participants examined social, obstetric, dietary, and anthropometric data using quantitative and qualitative methods. The analysis of fatty acids by gas chromatography revealed significant variability, with notable deviations in specific fatty acids like C:10:0 and C:12:0. Despite some differences, the overall composition aligns with standards. During pregnancy, 53.8% consumed five meals/day. Grilling (92.3%) and baking (76.9%) were common. Food consumption frequency differed from recommendations. Lactating mothers’ mean energy intake was 2575.88 kcal/day ± 730.59 standard deviation (SD), with 45% from carbohydrates and 40% from lipids, including 37.16 g ± 10.43 of saturated fatty acids. Diets during pregnancy lacked fruits, vegetables, legumes, nuts, and cereals. Lactating mothers partially met nutritional objectives, with an energy distribution skewed towards lipids and deficiencies in calcium, iodine, vitamin D, E, and folic acid. Promoting proper nutrition during pregnancy and lactation is essential to safeguard health and prevent chronic diseases.