Pre-pregnancy weight

Women with healthy eating and exercise patterns before pregnancy enjoy reduced health risks for both themselves and their babies during pregnancy.

How do I prepare for pregnancy?

By following a balanced diet and participating in regular exercise, you should work towards maintaining a Body Mass Index (BMI) below 30, and ideally between 20 and 25. Women who have BMIs over 30 when they conceive are at increased risk for complications during pregnancy.

What is BMI?

Body Mass Index (BMI) is used to estimate a healthy weight range for a person over 18 years of age, based on his or her height. Keep in mind that this measurement does not take into account factors such as genetics or bone structure, which will also influence a person’s weight. If you have concerns about your weight, speak to your health-care professional.

How do I calculate my BMI?

To calculate your BMI, and to see ranges for your optimal BMI, visit Health Canada’s BMI resource at the bottom of this page. You can also use this formula:

BMI = weight (kg) / height (m2)

Example: You are 160 cm tall and weigh 65 kg.

Body Mass Index

Obesity in pregnancy: what are the risks?

Having excess weight before pregnancy, particularly a BMI over 30, can increase your risk of serious health problems and is linked with many complications in pregnancy that affect both you and your baby.

Risks for you:

  • Gestational diabetes
  • Gestational hypertension
  • Caesarean section (as well as increased risks for complications)
  • Increased risk of excess blood loss
  • Early labour and birth
  • Miscarriage
  • Infertility

Risks for your baby:

  • Baby growing too big (causing problems during birth for mother and baby)
  • Difficulty monitoring fetal heart rate
  • Needing to stay in hospital after birth
  • Birth defects, including neural tube defects
  • Stillbirth

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