Dr Emma Derbyshire, an independent consultant to the Natural Hydration Council, says: "Adequate hydration is especially important during pregnancy and after birth to meet the physiological changes that occur during these important phases of the life-cycle.
"Water is needed to form amniotic fluid that surrounds the baby, support the increase in blood plasma volume and produce breast milk.
"Also, in the early stages of pregnancy, nausea and vomiting can lead to fluid losses, so it's important to keep water intakes topped up during this time.
"After birth, it's important to consider that every woman has slightly different water requirements, i.e. women who are breastfeeding exclusively will need to drink more water than women who are partially breastfeeding.
"Inadequate water intake during this time may lead to reduced milk volume, meaning there's less milk available for the baby.
"Overall, it's recommended that women should aim to increase their total water intakes by an extra 300ml/day during pregnancy and 700ml/day after birth, on top of the 2000ml/day total intake recommended by the European Food Safety Authority (EFSA).
"These fluids can come from both beverages and water-based foods sources such as soups, stews, yoghurts, fruits and vegetables."
For more information, see the Pregnancy and Motherhood factsheet at www.naturalhydrationcouncil.org.uk