Body temperature response to IL-1 beta in pregnant rats.

Rats have an attenuated or absent febrile response to exogenous pyrogen (e.g., bacterial endotoxin) near term of pregnancy. With the aim of providing insight into possible mechanism(s) of the altered febrile response to exogenous pyrogen, experiments have been carried out on 67 time-bred Sprague-Dawley rats to investigate the febrile response to endogenous pyrogen [i.e., interleukin-1 beta (IL-1 beta)]. On day 13 of gestation, intravenous injection of IL-1 beta produced a significant increase in body temperature with a latency of approximately 30 min and a duration of approximately 120 min. In contrast, on days 17 and 21 of gestation as well as on the day of delivery, intravenous injection of IL-1 beta produced significant decreases in body temperature. Thus rats do not develop fever in response to endogenous pyrogen near term of pregnancy but rather become hypothermic. The mechanism of the altered body temperature response to exogenous pyrogen as pregnancy proceeds remains unknown. We speculate, however, that it most likely lies downstream from the formation of endogenous pyrogen.

Association between congenital foot anomalies and gestational age at amniocentesis.

OBJECTIVES: Our objectives were to confirm the reported association between early amniocentesis and congenital foot anomalies as well as to report, for the first time, on the outcome of amniocenteses performed during the 13th and 14th weeks of gestation. METHODS: We conducted a triple cohort retrospective study of 4457 amniocenteses. Cohort definitions: early amniocentesis (EA), 11 weeks and 0/7 days to 12 weeks to 6/7 days; early midtrimester amniocentesis (EMA), 13 weeks and 0/7 days to 14 weeks and 6/7 days; and midtrimester amniocentesis (MA), 15 weeks and 0/7 days to 19 weeks and 6/7 days. Outcome measures were obtained by searching the Alberta Congenital Anomalies Surveillance System (ACASS) database for children born with foot anomalies represented by International Classification of Diseases version 9 (ICD-9) codes 754.5, 754.6 and 754.7. RESULTS: Incidences of congenital foot anomalies were: EA 11/980 (1.1%), EMA 11/2515 (0.4%), and MA 1/962 (0.1%). There is a significant difference between the EA and EMA cohorts (p=0.019) and between the EA and MA cohorts (p=0.003); however, these data suggest there is no difference between EMA and MA cohorts (p=0.11). CONCLUSIONS: Our incidence of congenital foot anomalies of 1.1% for women who underwent EA is similar to previously reported data, which further validates this association; however, our data also suggest that the foot anomaly risk may be limited to amniocenteses performed before the 13th week of gestation.