If you are significantly underweight or overweight, consult a dietician before you get pregnant. If you have a history of bulemia or anorexia, discuss this with your clinician. Unless you are significantly underweight, you will not need additional calories prior to your pregnancy.
Some clinicians, use a simple calculation as a beginning point in a discussion about your weight and nutrition. It is called the Body Mass Index, or BMI. Although the BMI is used primarily in determining risks for high blood pressure and heart disease, it can give your clinician (and you) a reference point for a discussion about your weight before and during pregnancy.
BMI= your weight in pounds X 0.455 / (height in inches X 0.0254)2
If you’d rather not do the math, check this link for your BMI.
If your BMI is less than 20 or over 26, you should discuss your weight and nutrition with your midwife or doctor.
If you have ever been diagnosed with anorexia nervosa, or if you have ever induced vomiting (made yourself throw up) as a way to control your weight, you should discuss this with your health care clinician.