Background Attaining greater peak bone mass (PBM) prior to the onset of bone loss is getting increasing public health attention as healthy strong bones are essential to maintain our life. Females are more susceptible to bone loss. Knowledge and awareness about low peak bone mass and its related risk factors are important contributors to its preventive behavior. Objective To screen apparently healthy young Kuwaiti future mothers for low bone mineral density (BMD) and to assess their knowledge level about determinants of PBM and preventive practices. Methods A cross-sectional comparative study on 445 eligible women aged 18–35 years (either students or employees from Kuwait University) was performed. Data on socio-demographic and lifestyle variables were obtained by a semi-structured questionnaire. Their knowledge was assessed using the modified Osteoporosis Knowledge Assessment Tool (OKAT). Bone mineral Density (BMD) was measured using Quantitative Ultrasonography (QUS). Results More than half (59.3%) of females had poor knowledge. A statistically significant relation was noted between the overall knowledge score and age, college, occupation, and socioeconomic class ( P <0.05 for each). Only 13.9% have low Z-score by QUS. By logistic regression, less carbonated beverages and coffee consumption positively affect BMD, while inadequate exercises level, indoor exposure to sunlight, and less frequency of brisk walking negatively affect BMD. Conclusion Unacceptable knowledge score significantly associated with BMD Z-score status. More attention should be devoted to education programs targeting adolescents and young females to promote knowledge about PBM and practice towards accrual and maintenance of bone health.