Why is weight loss before pregnancy important?

Answer From Yvonne Butler Tobah, M.D.

Part of having a healthy pregnancy is focusing on health before conception. Achieving a healthy pre-pregnancy weight can improve a person's chances of getting pregnant and minimize the risk of pregnancy complications.

Obesity — defined as having a body mass index (BMI) of 30 and higher — can decrease the chances of having regular ovulation. Obesity can also affect the outcome of in vitro fertilization (IVF). As BMI increases, so does the risk of unsuccessful IVF.

Obesity during pregnancy increases the risk of various pregnancy complications, including:

  • The risk of miscarriage, stillbirth and recurrent miscarriage
  • Gestational diabetes
  • A pregnancy complication characterized by high blood pressure and signs of damage to another organ system, often the kidneys (preeclampsia)
  • Heart problems
  • Sleep apnea
  • A difficult vaginal delivery
  • The need for a C-section and the risk of C-section complications, such as wound infections

In addition, a person's pre-pregnancy BMI affects recommendations for weight gain during pregnancy. If you have a BMI of 25 to 29.9, it's typically recommended to gain 15 to 25 pounds (about 7 to 11 kg) during pregnancy. If you have a BMI of 30 or more, it's typically recommended to gain 11 to 20 pounds (about 5 to 9 kg) during pregnancy.

To lose weight before pregnancy:

  • Schedule a preconception appointment
  • Eat a healthy diet
  • Consider talking to a registered dietitian or obesity specialist
  • Get at least 150 minutes a week of moderate aerobic activity or 75 minutes a week of vigorous aerobic activity, or a combination of moderate and vigorous activity — preferably spread throughout the week


Yvonne Butler Tobah, M.D.

April 19, 2022 See more Expert Answers