Purpose <p>This study investigated adherence to vitamin and dietary supplement intake, satisfaction with healthcare-provided information, and knowledge of essential micronutrients among women seeking fertility treatment and pregnant women in Germany.</p> Methods <p>An anonymous online survey (34 questions) assessed sociodemographics, supplement intake, knowledge and motivations. Adherence and satisfaction were measured by MARS-D (Medication Adherence Rating Scale) and SIMS-D (Satisfaction with Information about Medicines Scale).</p> Results <p>Among 254 participants, 93.7% reported supplement use, and 86.6% began intake preconceptionally. On average, participants consumed two (2.0 ± 1.36) supplements concurrently. Most multiple micronutrient supplements (MMS) contained folic acid (100%) and iodine (86.2%) at recommended doses, other nutrients varied considerably. Participants knew two (1.81 ± 1.43) out of six micronutrients prior to information provision, increasing to three (2.94 ± 1.65) afterwards. Satisfaction with information (SIMS-D: 7.46 ± 5.92) was low, whereas adherence was high (MARS-D: 27.16 ± 3.06). Higher information satisfaction was associated with pregnancy (<i>p</i> = 0.007), younger age (<i>p</i> = 0.009), and lower educational level (<i>p</i> = 0.024). Adherence was linked to trimester (<i>p</i> = 0.007) and region (<i>p</i> = 0.013), with higher MARS-D scores in the first trimester and among participants from North Rhine-Westphalia. Key motivations were protecting the child and preventing deficiencies; main barriers included lack of awareness and feeling overwhelmed by preparation oversupply.</p> Conclusions <p>Despite high adherence, knowledge and satisfaction with information remain limited. The wide variability in MMS formulations may pose risks of over- or underdosage. Combining personalized consultations with trustworthy media resources is essential to assess individual needs and provide detailed recommendations.</p>