A new Swedish study finds that pregnant women who consume too much water during labor are at greater risk of hyponatraemia, a potentially dangerous condition that results when an excess of water causes levels of sodium in the bloodstream to fall.
The study revealed that women who drank more than 2.5 liters during labor had a 25 percent greater chance of hyponatraemia, which can produce nausea, vomiting, headaches or more dangerous problems if left unchecked. In severe cases it can cause swelling of the brain or even coma.
The study tracked 287 participants who were allowed to drink freely during labor. Researchers took blood samples upon hospital admission and again after the birth. In total, 61 women consumed more than 2.5 liters of water, 16 of which were found to have hyponatraemia.
“We conclude that hyponatraemia is not uncommon following labor, and is potentially harmful, but is also easily avoidable,” said Dr Vibeke Moen of the Sweden’s Karolinska Institute, who led the study.
“Women should not be encouraged to drink excessively during labor, and the policy of liberal fluid administration should be questioned.”
Dr. Meon said further research is needed on whether lower blood sodium levels are linked with longer labors, as it might be influencing the ability of the womb to contract.
“At one time, a myth became prevalent that drinking lots of water each day was a healthy habit,” said Professor Philip Steer, chief editor of the obstetrics and gynecology journal BJOG, which published the current study.
“However, recent research shows clearly that in general, one can trust one’s natural body messages, and that we only need to drink more when we feel thirsty.”
Professor Steer recommends that doctors and midwives monitor how much water women drink during labor.
Gail Johnson of Britain’s Royal College of Midwives told BBC News she was unaware of any trend among midwives to ask women to drink water when not thirsty. Some British midwives encourage women to sip, rather than drink a lot, of water during labor.
“We’re not encouraging women to drink massive amounts of water, although perhaps we might suggest they take a sip to keep their mouths moist,” she said.
“One of the reasons is that the stomach does not empty as efficiently during labor, so drinking lots increases the risk of vomiting.
“The key thing is for the woman to listen to what her own body is telling her – many women would not want to drink much at all.”
The study was published in the journal BJOG. An abstract can be viewed here.
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