06/25/2024
Don’t get dehydrated!
During the past decades, the term “dehydration” has become fashionable. It sounds serious, with a scientific connotation. We are frequently told about the benefits of consuming a great amount of fluid. The implied message is that we should drink without waiting for the sensation of thirst.
In fact, apart from rare and well-defined situations, worrying cases of dehydration are exceptional in everyday life. It has been demonstrated that most people can tolerate a 3-4% decrease in total body water without difficulty or adverse health effects.
Paradoxically, there is a widespread lack of interest in the opposite of dehydration, which is “water intoxication”. Excessive absorption of fluids provokes disturbances in electrolyte balance, resulting in a rapid decrease in serum sodium concentration (hyponatremia), and symptoms such as confusion, drowsiness and headaches. In fact, it cannot be classified as a frequent life-threatening health event.
From a practical point of view, the focus should be on the particular case of women in labour. Their posterior pituitary gland is releasing the water retention hormones oxytocin and vasopressin. This hormonal release may be interpreted as protective. As long as the kidneys do not produce significant amounts of urine, the bladder is remaining quasi empty. The positive mechanical effects are obvious. The release of water retention hormones during labour is also a way to explain that, as a general rule, women are not really thirsty during labour. If they consume significant amount of fluid, it is mostly an effect of advice provided by well-intentioned birth attendants, popular books or other modern ways to become informed. There are many anecdotes of women whose bladder had be catheterised during a “modern birth”. The bladder could hold up to a litre of urine!
Even during modern births without pharmacological assistance, minor cases of water intoxication are possible and may be diagnosed in retrospect. They are related to the popular watchword “Don’t get dehydrated!”
At a time when the practice of obstetrics is characterised by the high rates of labour induction, the main preoccupation should be about the possible complications of the large volumes of water often used as a vehicle for the water retention hormone oxytocin.
All these considerations are easily understood by those who know that hormones released by the posterior pituitary gland are anti-diuretic and who heard about water intoxication.
Michel Odent. Author of “Can humanity survive socialised birth?”
