Group-based physical activity interventions for postpartum women with children aged 0-5 years old: a systematic review of randomized controlled trials.

BACKGROUND: It is estimated that less than one third of women (28%) worldwide, are not sufficiently active, and there is evidence indicating physical activity (PA) participation is lower during pregnancy and the postpartum period. Despite the importance of educating and encouraging postpartum women to engage in PA, existing systematic reviews have only focused on examining the impact of individually tailored PA interventions and on specific postpartum populations such as women who are inactive (i.e., do not meet PA recommendations) or women at risk of gestational diabetes mellitus or postnatal depression. This review aims to fill this gap by examining the impact of group-based PA interventions on postpartum women's PA levels or other health behavior outcomes. METHODS: A systematic literature search was conducted using four electronic databases (MEDLINE, CINAHL, EMBASE and PsychInfo) of published studies between 1st January 2000 and 31st October 2020. Studies were included if they targeted postpartum women with no current health conditions, had children aged 0-5 years, and engaged postpartum women in a group-based PA program that reported PA or other health behavior outcomes. Out of a total of 1091 articles that were initially identified, six were included. RESULTS: Group-based PA interventions were moderately successful in changing or increasing postpartum women's self-reported PA levels and psychological wellbeing in the first 2 years of their offspring's life. Overall, group-based PA interventions were not successful in changing or increasing postpartum women's objectively measured PA levels, but only one study objectively measured postpartum women's PA levels. Narrative synthesis highlights the heterogeneity of the outcomes and methodologies used, and the low to medium risk of bias in the included studies. CONCLUSION: To strengthen the evidence-base for group-based PA programs with postpartum women there is an on-going need for more rigorous randomised controlled trials of appropriate length (at least 3 months in duration) with an adequate dose of group-based PA sessions per week (to meet PA guidelines), and that utilise objective measures of PA. In addition, future PA interventions for this population should include, at the very least, fidelity and process data to capture the characteristics or design features that appeal most to postpartum women.

Histocompatibility difference between C3HfeB/HeN and C3H/HeN mice: tumour induced in C3HfeB/HeN mice expresses C3H/HeN-associated alloantigen.

A transplacentally induced lung tumour of C3HfeB/HeN mouse origin expresses, as a tumour-associated antigen, a normal tissue component of strain A mice. The genetic locus coding for this alloantigen has been shown to be linked to the H-2 major histocompatibility complex. In the present study we demonstrate that this antigen is also expressed on normal tissues of C3H/HeN mice. Skin grafts exchanged between C3HfeB/HeN and C3H/HeN mice are reciprocally rejected at approximately 3 weeks after grafting. C3HfeB/HeN mice were derived from C3H/HeN mice in 1945. These strains have apparently deviated since then in their genetic regulation of the expression of the MHC-linked genetic locus. The finding of the C3H/HeN-associated antigen on a C3HfeB/HeN mouse-derived lung tumour indicates that this deviation is reversible.

Normal tissue alloantigens and genetic control of susceptibility to tumors: microcytotoxicity studies on resistant C3Hf and susceptible (A X C3Hf) F1 mice inoculated with transplacentally induced C3Hf lung tumor.

The immune response of mice to a transplacentally induced lung tumor was investigated with the microcytotoxicity (MC) assay. The tumor, originally induced in C3Hf mice, does not grow readily when transplanted to normal syngeneic C3Hf recipients. It grows readily, however, in (A C3Hf)F1 hybrids and in strain C3H mice, which express in their normal lung tissue a component which constitutes a strong lung tumor-associated transplantation antigen (TATA) in C3Hf mice. Both lung tumor-immunized C3Hf and tumor-bearing (A X C3Hf)F1 and C3H mice possessed lymphoid cells reactive against cultured lung tumor cells in the MC assay. Reactivity was also observed against cells cultured from normal lungs of (A X C3Hf)F1 and C3H mice, but not against cells similarly cultured from C3Hf of C57BL/6 mice. Anti-tumor MC was inhibited by serum-blocking factors present in some but not all tumor-bearing and tumor-immunized mice. The MC assay and detection by it of serum-blocking factors does not distinguish the effective anti-C3Hf lung tumor immune response of immunized C3Hf mice from the ineffective immune response of tumor-bearing (A X C3Hf)F1 and C3H mice. Furthermore, in lung tumor-bearing mice cells reactive in the MC assay may be directed against a normal tissue antigen rather than a tumor-associated antigen.