The BMI scale uses the same categories for women and men (18.5-24.9 is normal). However, women naturally carry more body fat than men at the same BMI. A BMI of 22-23 is often considered ideal for women's long-term health.

BMI should not be used during pregnancy as weight gain is expected and healthy. Doctors use pre-pregnancy BMI to assess health risks and guide recommended weight gain during pregnancy, which varies by BMI category.

Waist-to-height ratio captures abdominal fat distribution, which is a stronger predictor of metabolic health risks than BMI alone. For women, a ratio under 0.5 is considered healthy, while above 0.6 indicates increased risk.