Drinking extra liquids while breastfeeding

Do I need to drink more while I am breastfeeding?

Mothers do need to drink more when breastfeeding, but their body will let them know how much. It depends on how much milk they are producing. Mothers can simply drink when thirsty and the body will take care of the rest. Forcing themselves to drink a lot of water will not increase the milk supply. In the first months after giving birth, mothers often feel suddenly thirsty when the baby starts to breastfeed. This is a reflexive thirst that ensures mothers have enough water in their body to make milk. It will decrease over time. Having water nearby when breastfeeding is helpful. 

A) Drinking enough liquids

The amount of extra water mothers require to breastfeed depends on the amount of milk they are producing. Human milk is roughly 87% water so that roughly 700 millilitres (24 U.S. fluid ounces) of water is needed to make 800 ml (27 U.S. fl oz) of milk (EFSA 2010).

The body monitors and closely controls the water balance. Mothers can simply drink when thirsty and the body will do the rest. Forcing themselves to drink large amounts of water will not increase the milk supply but it will send mothers to the bathroom. One study (Dusdieker 1985) found that milk supply did not change when mothers drank extra water.

B) Thirst with let-down

Mothers often feel suddenly thirsty when the baby starts to breastfeed in the first few months after the baby’s birth. 

The let-down triggers this thirst but the exact mechanism is not known (Amabebe 2017; James 1995). This reflex ensures that mothers have enough water in their body to make milk. 

It can help to keep a bottle of water within arm’s reach when this happens. This reflexive thirst will decrease with time.

C) Limiting food and liquids

Breastfeeding mothers are at a greater risk of becoming dehydrated in hot climates (Rosinger 2015).

One study (Prentice 1984) found that mothers who did not eat or drink anything (fasting) for 12 hours over three days continued to make the same amount of milk but that it contained slightly less milk sugar (lactose) and slightly more of salt. Mothers whose access to liquids and foods is severely limited may have a decrease in milk supply. 

References

Amabebe E, Robert FO, Obika LFO. Osmoregulatory adaptations during lactation: Thirst, arginine vasopressin and plasma osmolality responses. Niger J Physiol Sci. 2017 Dec 30;32(2):109-116

Dusdieker LB, Booth BM, Stumbo PJ, et al. Effect of supplemental fluids on human milk production. J Pediatr. 1985 Feb;106(2):207-11
 
EFSA Panel on Dietetic Products, Nutrition, and Allergies (ESFA). Scientific Opinion on Dietary reference values for water. EFSA Journal 2010; 8(3):1459, 48

James RJ, Irons DW, Holmes C, et al. Thirst induced by a suckling episode during breast feeding and relation with plasma vasopressin, oxytocin and osmoregulation. Clin Endocrinol (Oxf). 1995 Sep;43(3):277-82

Prentice AM, Lamb WH, Prentice A, et al. The effect of water abstention on milk synthesis in lactating women. Clin Sci (Lond). 1984 Mar;66(3):291-8

Rosinger A. Dehydration among lactating mothers in the Amazon: A neglected problem. Am J Hum Biol. 2015 Jul-Aug;27(4):576-8