Spinal anesthesia is the preferred anesthetic technique for patients undergoing cesarean section. Compared with general anesthesia, spinal anesthesia offers multiple advantages. However, a common adverse effect of this technique is hypotension following spinal anesthesia, which is induced by sympathetic blockade and has an incidence rate as high as 70%. Hypotension can lead to maternal nausea and vomiting, reduced fetal Apgar scores, and acidosis, exerting adverse effects on both the mother and the fetus. Furthermore, prolonged duration of hypotension may adversely impact the fetal neurological prognosis. Therefore, predicting which patients are at high risk for developing hypotension facilitates the implementation of preventive measures-such as the administration of vasoactive agents and intensified monitoring through frequent blood pressure measurements-to improve clinical outcomes in these high-risk patients.

Patients undergoing cesarean section who met the inclusion criteria were prospectively observed. A standardized anesthesia protocol was uniformly applied to investigate the incidence of hypotension following spinal anesthesia. Based on dynamic changes in preoperative and intraoperative heart rate, blood pressure, perfusion index, and waveform characteristics of electrocardiography and pulse oximetry, a prognostic model was developed to predict the occurrence of hypotension after spinal anesthesia.

Inclusion Criteria:

• Singleton pregnant women aged ≥18 years with gestational age ≥37 weeks, scheduled for cesarean section.

Informed consent was obtained from all participants.

Exclusion Criteria:

• Emergency cesarean sections or cases requiring general anesthesia. Maternal age < 18 years. Major obstetric complications (e.g., placenta previa, gestational hypertension, preeclampsia) or significant cardiovascular/cerebrovascular diseases.

Body Mass Index (BMI) ≥ 36 kg/m². Gestational age < 36 weeks or > 41 weeks. Contraindications to neuraxial anesthesia. Refusal to participate.

Singleton pregnant women aged ≥18 years with gestational age ≥37 weeks, scheduled for cesarean section.