Exercise and breastfeeding: Effects on breast milk composition and infant health

Exercise and breastfeeding: Effects on breast milk composition and infant health

The aim of this study is to determine if exercise after delivery influences breast milk composition among and infant growth and health.

The study starts 5-6 weeks after delivery. It is good if potential participants contact us before this time. The participants will be randomly allocated to one of two groups:

  1. Intervention group: Endurance exercise with moderate to high intensity, 2-4 times per week for 8 weeks. The training will be adjusted to your cardiorespiratory fitness level. You will receive guidance and supervision from study collaborators, and we will watch your baby during the exercise sessions.
  2. Control group: No intervention, just continue with habitual living.

The study period is approximately 8 weeks, but with follow-up of the infant until 2 years of age.

Criteria for participation:

  • 18 years old or more
  • BMI: 25 kg/m2 or more before pregnancy, or 28 kg/m2  or more after delivery
  • Exclusively breastfeeding
  • Living in the Trondheim area
  • Understands oral and written Norwegian

The study implies that we will obtain fasting blood samples from you, estimate your body composition (the amount of muscle and fat), measure your blood pressure and your cardiorespiratory fitness level, at baseline and after 8 weeks. At the start of the study, after 4 weeks, and after 8 weeks, we will collect breast milk samples. You will get an electrical breast milk pump. You will be asked to complete some questionnaires (about physical activity, breastfeeding, and psychological well-being) at baseline and after 8 weeks.

We will also record information about your baby (birth weight, length, head circumference, and sex), and assess its body composition using bioimpedance at the start of the study and after 4 and 8 weeks. At the start of the study, and after 8 weeks, will we also obtain a sample (a few drops) of blood from your baby using heel prick. We will collect faecal samples from your baby at start of the study, after 4 weeks and 8 weeks, as well as when the infant is 6, 12, and 24 months old. In the follow-up period until the infant is 24 months old, we will ask you to complete three questionnaires, one when the child is 6 months, one when it is 12 months, and one when it is 24 months old. In these questionnaires we ask about the infant’s nutrition and the growth measurements that have been completed at the health care centres. 

The project is completed at the Faculty of Medicine and Health Sciences, NTNU, in collaboration with the Women’s Clinic at St. Olavs Hospital, and is approved by the Regional Committee for Medical and Health Research Ethics (REK).  



Trine Moholdt
Researcher Scientist and Head of the Exercise, Cardiometabolic Health and Reproduction Research Group