The investigators aimed to compare the methods colloid preloading and colloid coloading in terms of the incidence of maternal hypotension and impacts on neonatal outcomes. The second aim while planning the present study is to identify the method of the lowest adverse event for mother and infant and the simplest approach for the clinician.

Spinal anesthesia (SA) is currently the most preferred method of anesthesia in elective cesarean deliveries. However, SA causes maternal hypotension by decreasing systemic vascular resistance over sympathetic blockade. Maternal hypotension can lead to serious adverse events both in mother and in fetus: fetal hypoxia and acidosis occur due to decreased uterine blood flow, whereas the mother may experience vertigo, nausea, vomiting, alteration in consciousness, cardiovascular collapse and arrest. Today, various strategies have been suggested for the prevention of maternal hypotension. Of these strategies, the most critical ones are fluid load before spinal anesthesia (preloading) or rapid fluid load just after spinal anesthesia (coloading) and the use of vasopressor agent. The fluids used for this purpose include crystalloids and colloids. Comparative studies performed with colloid preloading, colloid coloading and crystalloid coloading indicated that the incidence of hypotension decreased similarly with no significant difference determined between the methods of fluid loading. Researchers defended necessity of using vasopressor agent together with fluid loading methods. In daily routine; however, the investigators observe that the incidence of hypotension is lower in the patients that undergo colloid preloading as compared to the patients that undergo colloid coloading or crystalloid coloading. The investigators therefore aimed to compare the methods colloid preloading and colloid coloading in terms of the incidence of maternal hypotension and impacts on neonatal outcomes. In the present study, the investigators aimed to use 6% HES 130/0.4 (Voluven ®), which is the newer generation colloid solution. The other aim while planning the present study is to identify the method of the lowest adverse event for mother and infant and the simplest approach for the clinician.

Inclusion Criteria:

• Age 18 years or older
• Singleton pregnancy
• Gestational age ≥ 37 weeks
• Height ≥ 150 cm and ≤ 180 cm
• Weight > 50 kg and < 100 kg

Exclusion Criteria:

• Gestational age > 37 weeks
• Multiple pregnancies
• Fetal distress
• Preeclampsia
• Cardiovascular disease and diabetes
• Hematological problems
• Local infection at intervention site
• Abnormal coagulation tests
• Anticoagulant use
• Starch allergy
• Height < 150 cm and > 180 cm
• Weight < 50 kg and > 100 kg