Weight Management Weight management support Your chances of becoming pregnant and having a healthy pregnancy are improved if you are a healthy weight (Body Mass Index between 18.5 and 25) before you become pregnant. You can read more here. Maintaining a healthy weight will also reduce the chance of your children becoming overweight. The national guidelines do not recommend dieting during pregnancy, but weight management support services are available to help you eat well and be physically active during pregnancy, and to help you lose weight after the birth. Your midwife can generally refer you if your Body Mass Index (BMI) is 30 or more. If your BMI is between 25 and 30 but you are very interested, referral may also be possible – speak with your midwife or directly with the service in your area.