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Multiple gestation
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
All animals, including the Homo sapiens, demonstrate an inverse relationship between litter size and both gestational age and birth weight. In the human, the average gestational age at birth is around 40 weeks for singletons, 36 weeks for twins, 32 weeks for triplets, and 29 weeks for quadruplets. Although multiple pregnancies exhibit many specific complications, the consequences of prematurity are by far the most common and are the most important public health concern.
Radiation Hormesis in Reproduction
Published in T. D. Luckey, Radiation Hormesis, 2020
Brown gave summary data for the litters from 4 successive pregnancies in 30 control females of the 12th generation; they were compared with data from 4 rats of the 12th generation exposed to 2 cGy/d.111 The percent of exposed females which cast litters was 117% greater than that of controls. The average litter size from exposed females was 157% of that of controls. The average weight of pups cast from exposed females was 110% of that of controls, and the total weight of the litter from exposed females was 172% of that of controls. The average number weaned from exposed females was 147% greater than controls. The total weight of young at weaning averaged 137% greater for the exposed females when compared with unexposed controls. Although statistics were not utilized, this is good evidence that 2 cGy/d was hormetic for various parameters of reproduction.
Pharmogenology: The Industrial New Drug Development Process
Published in Gary M. Matoren, The Clinical Research Process in the Pharmaceutical Industry, 2020
Female rats are dosed for 14 days prior to pairing, and half of these are sacrificed in midpregnancy to evaluate the number and state of embryos. The other females are allowed to litter and are studied for litter size, survival of pups, and gross anomalies. Thus, Segment I studies provide information concerning drug action on the entire reproductive process including teratogenesis, late stages of gestation, parturition, lactation, and weaning.
Nutritional stress timing differentially programs cognitive abilities in young adult male mice
Published in Nutritional Neuroscience, 2022
Bruno G. Berardino, Fabricio Ballarini, Mariela Chertoff, Lionel M. Igaz, Eduardo T. Cánepa
Parents were randomly assigned (by means of a computer-based method) to either the NP or the LP group. The animals were identified by earmarks and numbers, which were announced to the researcher only after finishing the experiments and analyses. Both female and male F0 mice were fed with the NP or the LP diet during the mating period, after which dams were kept on the same diet during pregnancy and lactation. Female parents were weighed every day at 10:00 am. Efforts were made to balance the litter size within a range of 8–10 pups per dam on PD2 (mean litter size: NP = 10.00; LP = 9.17). Pups were weaned on PD21 and housed under the standard chow diet for five weeks, i.e. until PD56. The perinatal diet was the factor that constituted the two levels of the treatment: perinatal normal-protein diet (NP-P) and perinatal low-protein diet (LP-P). F1 male mice were used for behavioral testing during the 8th to 10th weeks of age. Some animals died due to infant cannibalism between birth and PD2 (NP-P: 1 mouse from 1 litter; LP-P: 7 mice from 3 litters). Then, litters were balanced between 8 and 10 pups (NP-P average litter size: 10.00; LP-P average litter size: 9.21). After PD2, 2 LP-P dams committed further infant cannibalisms and were excluded from the experiment. The total number of litters was 6 for NP-P group and 6 for LP-P group.
The influence of lunar cycle at the time of conception on sex offspring distribution in dogs
Published in Chronobiology International, 2021
Daniela Alberghina, Mauro Gioè, Marco Quartuccio, Luigi Liotta
The average litter size was 6.5 ± 2.6 and the sex ratio was 1.09 (509 males and 468 females). Borderline dates between seasons (± 1 week from change of the season) and between lunar phases at conception were excluded from analysis (n.40 borderline for seasons and n. 7 borderline for lunar phases). No correlation was found between the offspring sex ratio and the age of mother (r = 0.07, p = .35). The distribution of births was higher for conception in autumn and lower in summer and higher for conception in the new moon compared to other phases (Table 1). The statistical model did not detect an effect of season at conception (F3,94 = 1.167, p = .32, Figure 1) but did indicate a significant effect of lunar phase on offspring sex ratio (F3,94 = 3.393, p < .05); specifically, the ratio males/males + females in offspring conceived in the new moon phase were significantly lower than during the full moon phase (p < .05, Figure 2). No significant interaction between lunar phase and season was found (F9,94 = 0.598, p = .796).
Prenatal stress promotes insulin resistance without inflammation or obesity in C57BL/6J male mice
Published in Stress, 2021
Sofia Quiroga, Yamila Raquel Juárez, María Paula Marcone, María Agustina Vidal, Ana María Genaro, Adriana Laura Burgueño
Values were expressed as the mean ± standard error of the mean (SEM) for each group. Statistical analyses were conducted using STATISTICA 7.0 software (StatSoft, Inc., Tulsa, Oklahoma, USA). To analyze litter size, we used a t-test, and for other litter parameters χ2 test was used. The normality and homogeneity of variance for the dataset were tested using the Kolmogorov-Smirnov test and Levene’s test, respectively. In case the assumptions were not met, the data were transformed as appropriate. Differences between groups were analyzed using one-way ANOVA. When the time factor was also involved, repeated-measures ANOVA was used. If the transformed data did not comply with normality and/or homogeneity of variance, the non-parametric Mann-Whitney U test was used. In this case, the data were expressed as a median and interquartile range. When significant interactions were obtained, planned comparisons were used. Significance was determined at p < .05.