Spinal anaesthesia is the anaesthetic technique of choice for elective caesarean delivery. Hypotension, a result of the decrease in systemic vascular resistance caused by spinal anaesthesia, is a frequent complication occurring in up to 80%. This study is to investigate fluid loading plus vasopressors to vasopressors alone to maintain stable maternal haemodynamics in elective caesarean delivery. The effect of the two methods (continuous prophylactic phenylephrine infusion with and without crystalloid co-loading) on maternal haemodynamics will be compared using the Starling SV Monitor. The Starling SV device is a non invasive cardiac output monitor (NICOM) which is certified and validated for the use in pregnancy.

Inclusion Criteria:

• Ability to give informed consent
• Term uncomplicated singleton pregnancy
• Undergoing elective caesarean section under spinal anaesthesia
• Weight: 50-100kg
• Height: 150-180cm
• Healthy term fetus

Exclusion Criteria:

• Inability to give informed consent
• Multiple pregnancy
• Clinically significant concomitant disease states (e.g. hypertension, cardiac disease, severe asthma requiring regular medication, comorbidities affecting the autonomous nervous system, renal disease)
• On any cardiovascular medication
• Complications of pregnancy (e.g. preeclampsia, intrauterine growth restriction, fetal malformations)
• Known or suspected non-compliance, drug or alcohol abuse
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia of the participant,
• Participation in another study with investigational drug within the 30 days preceding and during the present study,
• Previous enrolment into the current study,
• Enrolment of the investigator, his/her family members, employees and other dependent persons
• Any fetal pathology (e.g. fetal malformations, rupture of membranes before caesarean section, oligohydramnios, polyhydramnios, suspected chorioamnionitis)

Investigator and participant cannot see to which study group the participant belongs. The person performing randomisation and fluid application will not be involved in the data collection and Analysis.