Medline ® Abstracts for References 2,3

OBJECTIVE: To examine the theory that the postpartum shivering phenomenon is related to feto-maternal bleed during the third stage of labor.

METHODS: One hundred laboring low-risk women who had a normal vaginal delivery were observed for the presence of postpartum chills. The duration of the first and second stages of labor changes in body temperature, maternal and fetal blood types and the use of epidural anesthesia were recorded. Following the delivery maternal blood was examined for the presence of fetal red blood cells using the Kleihauer-Betke stain.

RESULTS: Complete data was available in 97 patients. Post-partum chills occurred in 31 of them (32%). Women with and without chills were similar in their maternal and gestational age, the use of epidural anesthesia, and length of second stage of labor. Women with chills delivered smaller babies but the difference did not reach significance. Maternal-fetal blood group incompatibility was significantly more common among shivering than non-shivering women (48% vs. 20% respectively, p=0.006). Kleihauer-Betke test was positive in 11 women. The only two women in this group who experienced chills had maternal-fetalblood group incompatibility.

CONCLUSION: Post-partum chills are a common phenomenon. It may be the clinical presentation of feto-maternal transfusion reaction. The small number of positive Kleihauer-Betke tests may reflect its low sensitivity in the detection of small feto-maternal bleeds.

OBJECTIVE: To describe the frequency, duration and timing of shaking rigors during parturition and their associations with several clinical variables.

STUDY DESIGN: A total of 467 term, singleton paturients at a single hospital over a 13-month recruitment period were observed by their labor nurses for shaking rigors. Thirteen clinical variables, including length of labor, were also recorded. Multiple regression procedures were used to evaluate associations with presence or absence, number and total duration of rigors. The relationship in time between shaking rigors and sentinel events in labor was also examined. With this sample size, we had>80% power to detect differences as small as 0.26 effect size units for continuous measures, or ORs of 1.75 or greater for categorical measures, when comparing patients with and without rigors.

RESULTS: In total, 57% of parturients experienced at least 1 rigor. Epidural usage was related to risk, duration and number of rigors. Increased maximum temperature was associated with an increased chance of rigors. Epidural, birth and maternal fever were antecedent events.

CONCLUSION: Over half of parturients experienced shaking rigors. Epidural administration and fever were associated with an increased probability of rigors and an increased number of episodes.