[1] Univ Calif San Diego, Dept Anesthesiol, Obstet Anesthesia, San Diego, CA 92103 USA
[2] Univ Calif San Diego, Dept Anesthesiol, Anesthesiol & Reprod Med, San Diego, CA 92103 USA
[3] Univ Calif San Diego, Dept Anesthesiol, Anesthesiol, San Diego, CA 92103 USA
[4] Univ Calif San Diego, Dept Reprod Med, Obstet Anesthesia, San Diego, CA 92103 USA
[5] Univ Calif San Diego, Dept Reprod Med, Anesthesiol & Reprod Med, San Diego, CA 92103 USA
[6] Univ Calif San Diego, Dept Reprod Med, Anesthesiol, San Diego, CA 92103 USA