The prevalence of immunization to Duffy antigens in a population of known racial distribution

A retrospective study at our hospital determined the race or ethnicity of patients seen in an 8-year period who had formed antibodies to Duffy antigens. During that time, 9876 serologic investigations had been performed as a result of a positive direct or indirect antiglobulin test. Among these samples, sera from 45 previously transfused or pregnant patients contained anti-Fya and two contained anti-Fy3. Twenty-nine of the sera that contained anti-Fya (62%) were from blacks, 12 (25%) were from whites, and 6 (13%) were from Hispanics. Both examples of anti-Fy3 were made by black patients. Red cells (RBCs) from 21 of the black patients were Fy(a-b-), those from 7 were Fy(a-b+), and those from 1 could not be phenotyped. RBCs from 17 of the non-black patients were Fy(a-b+) and those from 1 could not be phenotyped. The population of transfused patients evaluated in this study was 47 percent black, 29 percent white, and 24 percent Hispanic. Calculations based on an expected Fy(a-) frequency of 88 percent in blacks, 33 percent in whites, and 20 percent in Hispanics predict that the racial makeup of the Fy(a-) population at our hospital would be 73 percent black, 18 percent white, and 9 percent Hispanic, which is not significantly different (p = 0.25) from the racial makeup of the patients forming anti-Fya and -Fy3. These data indicate that blacks make antibodies to Duffy antigens as frequently as non-blacks.     

Maternal Temperature Elevation and Occiput Posterior Position at Birth Among Low‐Risk Women Receiving Epidural Analgesia

Introduction: To evaluate the relationship between maternal temperature elevation and occiput posterior position at birth as well as the association of fetal head position and temperature elevation on method of birth among women receiving epidural analgesia. Methods: We conducted a secondary analysis of data from the Fetal Orientation during Childbirth by Ultrasound Study (FOCUS), which used serial ultrasounds to evaluate the effect of epidural anesthesia on fetal position at birth in low‐risk women. The current analysis was limited to the 1428 study participants who received epidural analgesia. Results: In our population, 47% (n = 669) of women had a maximum intrapartum temperature greater than or equal to 99.6°F (37.6°C). The prevalence of fetal occiput posterior position at admission did not differ between women who later developed temperature elevations (24.4%) and those who did not (23.6%, P= .70). Women who developed an elevated temperature greater than or equal to 99.6°F (37.6°C) had an increased risk of occiput posterior fetal head position at birth regardless of the amount of temperature elevation (odds ratio [OR]= 2.0; 95% confidence interval [CI], 1.5‐2.8); the association persisted after control for potentially confounding factors (adjusted OR = 1.5; 95% CI, 1.1‐2.1). The cesarean birth rate among women with both temperature elevation and occiput posterior position at birth was more than 12 times the rate of women with neither risk factor (adjusted OR = 12.6; 95% CI, 7.5‐21.2). Discussion: Intrapartum temperature elevation among women receiving epidural analgesia, even if only to 99.6°F (37.6°C), is associated with approximately a 2‐fold increase in the occurrence of occiput posterior fetal head position at birth. Additionally, although this observational study cannot establish causal links, our findings suggest that the relationship between epidural‐related intrapartum temperature elevation and occiput posterior position at birth could contribute to an increased cesarean birth rate among women receiving epidural analgesia for pain relief in labor.