Efficacy of "optimal hydration" during labor: HYDRATA study protocol for a randomized clinical trial

There is a lack of consensus in the international scientific community with respect to the most suitable hydration strategies when attending nulliparous women during low-risk births. This paper describes the protocol for a randomized controlled trial to compare two hydration strategies and their influence on maternal and neonatal morbidity. The study population consists of nulliparous women admitted to the obstetrics department of a University Hospital. The women are being randomized into two groups: the "optimal hydration" group, which will be guaranteed 300 ml/hr liquids (crystalloids and bottled mineral water) with a minimum diuresis of 35 ml/hr; and the "variability in hydration" group, which will receive intravenous (alternating normal saline, Ringer's lactate solution, glucose, or Voluven®) and clear (bottled mineral water or isotonic drinks [Aquarius®]) liquids, without any established perfusion rate, and without established minimum diuresis. Outcomes for mothers include duration of labor, cesarean section, fever, and dehydration. Outcomes for newborns are respiratory distress, hypoglycemia, hyponatremia, jaundice, weight loss over 48 hr, and breastfeeding difficulties. Analysis will be per-protocol. Administering optimal hydration may improve health and safety for mothers and their newborn and reduce maternal and neonatal morbidity. The study is registered at www.clinicaltrials.gov. The project received funding by the Ministry of Health of Spain and is approved by the Research Ethics Committee.