Epidural analgesia is widely used for managing pain during labor. The programmed intermittent epidural bolus (PIEB) technique has been shown to produce less consumption of local anesthetics, better sensory block, less motor block, and increased maternal satisfaction than other epidural analgesia techniques. Despite all benefits from PIEB, such practice has been associated with high sensory block levels. Therefore, assessment of the sensory block level is an essential component of clinical safety. The lack of a standardized technique and timing to assess the sensory block level can lead to inappropriate management. The purpose of this study is to investigate the changes in block level over time, during cycles of a PIEB regimen. The investigators hypothesize that these levels will be highest soon after the PIEB bolus and lowest preceding the subsequent PIEB bolus. The investigators also want to investigate a possible correlation between these changes in sensory block levels and motor block, pain scores, and rescue bolus of local anesthetics.

Inclusion Criteria:

• women admitted to the Labor and Delivery unit at Mount Sinai Hospital that request and have no contraindications to receive epidural analgesia
• 18 years old or more
• capable of understanding and signing the written informed consent
• have no language barrier to respond to the level of sensory block assessment
• and have no conditions that could compromise the body sensitivity to cold.

Exclusion Criteria:

• unintentional dural puncture during labour epidural placement
• do not achieve adequate pain control 20 minutes after the loading dose (numeric rating scale (NRS)>1 on a 0-10 NRS),
• deliver before 160 minutes following the loading dose
• require rescue boluses in the first 80 minutes after initiation of PIEB (that is, before the 2nd PIEB bolus)
• withdraw their consent.

Women admitted to the Labor and Delivery unit at Mount Sinai Hospital that request to receive epidural analgesia.