ORIGINAL ARTICLE: How Should Data on Murine Spontaneous Abortion Rates be Expressed and Analyzed?

Abstract

Although it is possible to compare individual mice, and even individual implantation sites, in resorption (abortion) studies, as the relevant question is the significance of differences between treatment groups of mice, and reproducibility, the established classical method of reporting R/T should continue to be provided. In CBA x BALB/c matings, where abortion rates are low, using the median is misleading and may obscure the existence of two distinct populations.

Early detection and staging of spontaneous embryo resorption by ultrasound biomicroscopy in murine pregnancy

“…Up to date, studies on embryo resorption are performed mainly post mortem [10-12] and pregnant animals are sacrificed at certain days of pregnancy to determine the resorption rate. The resorption rate is defined as the ratio between the number of resorptions and the number of normal implantations [13]. The inaccuracy of this method is rooted in the uncertain time point of embryonic death.…”

To drive or be driven: the path of a mouse model of recurrent pregnancy loss

“…Data on litter size is not as prevalent as data on what is called “resorption. Pregnancy loss in the CBA/J x DBA/2 model is usually reported as the number (or percent) of resorptions/total number of implantations (R/T), pooling data from individual mice (Clark, et al 2008b) and this is deemed preferable to reporting median and range of resorbed units or to comparing data from individual mice. The percentage of resorbing fetal-placental units in this mating are highly variable, with some values as low as 10 % and others upwards of 80% depending on several factors—in particular, the microbial barrier status of husbandry { Hamilton, 1987 #73;Clark, 2003 #168 }.…”

Betaine Homocysteine Methyltransferase Is Active in the Mouse Blastocyst and Promotes Inner Cell Mass Development

“…The numbers of fetuses and resorption sites were determined for each pregnant recipient, and data from individual recipients were pooled for analysis as categorical data, as recommended (33). There was no significant difference in the embryo implantation rate in pregnant recipients between treatments (data not shown; p ϭ 0.13).…”

“…Pregnancies (fetuses or resorption sites) were found in 12 recipients in the control morpholino group and 14 in the BhmtMO1 morpholino group. Numbers of fetuses and resorptions were pooled for each group and analyzed in a 2 ϫ 2 table, as recommended (33). The control group had 70 fetuses and 12 resorption sites, and the Bhmt morpholino group had 60 fetuses and 49 resorption sites, shown as percentages of the total.…”