Exercise and breastfeeding

Exercise is an important part of life for many mums, including those who are breastfeeding. It can be difficult to fit exercise into your busy day and you may also often feel tired. Walking may be the simplest form of exercise to plan into your day. 

Some mums find it motivating to join a pram walking group, while others choose to walk to the local café or shops to meet up with friends in the area. 

However, you might be worried about whether exercise will affect breastfeeding. 

Exercise assists in the wellbeing of new mums in many ways. For example, exercise can: 

• improve your heart health¹ and general fitness² 
• improve your mental wellbeing and energy levels³
• reduce stress levels³ 
• assist with weight control³  
• improve your bone strength⁴ 
• assist with the treatment of post-natal depression^5,6

Moderate exercise won’t affect  

• breastmilk supply^2,9 

• levels of lactic acid^7,8  

• important immune factors (SIgA, lactoferrin, and lysozyme)¹⁰ 

• major nutrients (fat, protein, lactose) or energy density⁹ 

• major minerals (calcium, phosphorous, magnesium, potassium and sodium)¹¹ 

Some mums are concerned about lactic acid build up after exercise and whether this affects their breastmilk. Mild or moderate exercise does not cause lactic acid to increase in breastmilk and does not affect a baby taking the milk.

Intense (maximal) exercise can cause an increase of lactic acid but there is no evidence to suggest that breastmilk with increased lactic acid levels will harm your baby in any way. 

Exercising and breastfeeding won’t have any effect on the growth of your baby.¹² If you need to lose weight, doing moderate exercise 4 days per week to help lose 0.5kg per week won’t affect your baby’s growth.² It’s helpful if your breastfeeding is well established first before you start exercising.  

Your body is designed to carry a baby through pregnancy, give birth and breastfeed. Hormonal changes in pregnancy and childbirth allow the ligaments in your pelvis to loosen so that your baby can be born.   

After birth, many of these hormones are no longer needed and so their levels drop off. Various hormonal, postural and muscular changes that occur during pregnancy and childbirth may play a role in causing various musculoskeletal conditions (eg pelvic floor or abdominal muscle weakness, or ‘loose ligaments’).

For some women these changes may cause pain (particularly in the pelvic or lower back regions) or other problems (eg incontinence). For some women, these problems may continue for a period of time after birth.  

If you have any of these conditions you may benefit from seeing a physiotherapist. They can advise you on ways to relieve the condition and give you some suitable exercise.  

There is no evidence to suggest that breastfeeding makes any of these conditions worse.  

Research has found that breastfeeding after vaginal childbirth is not associated with the development of incontinence or pelvic organ prolapse.¹³