During pregnancy the person’s blood volume increases by approximately 50%. The extra blood helps support the placenta and brings the baby the nutrients and oxygen they need to develop. Blood has hormones flowing through it at all times and the amount of hormones can vary.
Oxytocin (the love hormone) is one hormone that flows through the blood and triggers uterine contractions. When there is a rise in oxytocin, labour can be triggered. When a pregnant woman becomes dehydrated the blood volume decreases. This triggers the oxytocin that is in the blood to elevate which can trigger contractions.
In most cases, when the pregnant woman rehydrates, the contractions halt meaning the person’s body and baby aren’t yet ready for labour. Oral hydration usually solves this but, in some cases, the pregnant person’s care provider may recommend IV hydration.
Dehydration can cause nausea, dizziness, weakness and fatigue and shouldn’t be used as a way to start labour due to that fact that contractions usually go away or aren’t strong enough once rehydrated rather orally or by IV.
You can prevent dehydration by drinking plenty of fluids and eating fruits and vegetables high in water such as cucumbers, oranges and grapes.