I've put on around 30 pounds during pregnancy and I'm planning to start an exercise program to help with the weight loss. I've heard that the lactic acid buildup during aerobic exercises will pass into breastmilk as well as accumulate around joints. This lactic acid will turn the taste of milk to sour and thus causing the baby to reject breastfeeding. Will exercise cause difficulties with breastfeeding?
Two studies (Wallace, et al, 1991 and 1992) were published regarding refusal of breastfeeding following strenuous exercise. Lactic acid levels in breastmilk were found to increase following 30 minutes of aerobic activity. The increased lactic acid levels were reported to give a bitter sour taste to the normally sweet breastmilk. Babies in the study were less likely to accept samples of breastmilk with high levels of lactic acid (that were offered by dropper). Lactic acid levels were reported to remain elevated in milk for as long as 90 minutes.
The studies I have referred to were small. The 1991 study involved seven women and the 1992 study, 26 women.
More recent studies confirm that aerobic exercise does not have a negative affect on lactation.
"Aerobic exercise performed four or five times per week beginning six to eight weeks postpartum had no adverse effect on lactation and significantly improved the cardiovascular fitness of the mothers." (N Engl J Med 1994 Feb 17;330(7):449-453)
"Exercise sufficient to improve cardiovascular fitness without substantially altering energy balance does not adversely affect lactation performance." (Nutr Rev 1994 Oct;52(10):358-360)
"Aerobic exercise improves cardiovascular fitness and does not affect milk energy transfer to the infant." (J Nutr 1998 Feb;128(2 Suppl):386S-389S)
"Exercising subjects tended to have higher milk volume (839 vs 776 g/d) and energy output in milk (538 vs 494 kcal/d). Thus, there was no apparent adverse effect of vigorous exercise on lactation performance." (Am J Clin Nutr 1990 Jul;52(1):103-109)
Many women successfully combine moderate aerobic exercise with breastfeeding. Their babies nurse contently immediately following exercise.
If your baby refuses to nurse following your workout, the following suggestions have been adapted from the book, Breastfeeding - A Guide for the Medical Profession, Ruth Lawrence, MD, 1994:
- Shower or wash perspiration from your breasts;
- Hand express a few teaspoons of milk from each breast and discard;
- If your baby refuses to nurse, puckering his face, you can feed him with previously expressed breastmilk.
Best wishes with your exercise program!
