Prenatal yoga and excessive gestational weight gain: A review of evidence and potential mechanisms.

PURPOSE: To review the evidence of the potential mechanisms (behavioral, psychological/emotional, and physical factors) of prenatal yoga for preventing excessive gestational weight gain (GWG) in pregnant women to guide future research. MAIN BODY: Prenatal yoga is a common form of physical activity during pregnancy and includes a combination of physical postures, breath control and meditation. This review theorizes how combining physical activity (i.e., prenatal yoga postures) with the add-ons brought by prenatal yoga (e.g., breath control, meditation), might provide a more comprehensive and effective strategy to prevent excessive GWG than physical activity alone. This article a) summarizes the literature on potential mechanisms of prenatal yoga to prevent excessive GWG specifically focusing on behavioral (diet, physical activity, and sleep), psychological/emotional (self-awareness, emotion regulation, stress, mood, mindfulness) and physical factors (pregnancy discomforts), b) highlights limitations of current studies, and c) provides suggestions for future research. The findings demonstrate there is insufficient evidence that prenatal yoga improves behavioral, psychological/emotional and physical factors in pregnant women and more research is needed. Though these factors have been more strongly linked to improved weight outcomes in non-pregnant populations, further testing in pregnant women is necessary to draw definitive conclusions for the efficacy of prenatal yoga to prevent excessive GWG. CONCLUSION: Effective strategies are needed to prevent excessive GWG to encourage optimal maternal and child health outcomes. More research is warranted to evaluate the impact of prenatal yoga on weight outcomes during pregnancy and design studies to test the proposed mechanisms discussed in this review.

A qualitative investigation of a prenatal yoga intervention to prevent excessive gestational weight gain: A thematic analysis of interviews.

PURPOSE: To describe pregnant women's experiences and perceived facilitators/barriers of a prenatal yoga intervention to prevent excessive gestational weight gain (EGWG). METHODS: Pregnant women (N = 13) were interviewed after participation in a 12-week prenatal yoga intervention to prevent EGWG. Interviews were summarized using thematic analysis. RESULTS: Twelve themes were identified and organized into four categories: 1) experiences of prenatal yoga (positive experience/enjoyment, pain relief, connecting to body), 2) prenatal yoga and weight (increased mindfulness/self-awareness, increased physical activity, weight management), 3) barriers to prenatal yoga (physical body, commute/traffic, schedule), and 4) facilitators of prenatal yoga (healthy pregnancy, support from other pregnant women, the feeling from prenatal yoga). CONCLUSION: Prenatal yoga may relieve pain and help women be more connected to their bodies. Prenatal yoga may also help women become more aware of their health behaviors and increases their physical activity which may have important implications for reducing EGWG.

Intrauterine hypoxia upregulates proinflammatory cytokines and matrix metalloproteinases in fetal guinea pig hearts.

OBJECTIVE: Intrauterine infection increases proinflammatory cytokines in the fetus. We hypothesize that proinflammatory cytokines and matrix metalloproteinases (MMPs) are upregulated in fetal hearts in response to hypoxic stress. STUDY DESIGN: Timed-pregnant guinea pigs were exposed to either hypoxia (10.5% O(2), 14 day) or normoxia (room air). Left ventricles of fetal hearts were excised from anesthetized age-matched fetuses and frozen until ready for study. Messenger RNA of pro- (TNF-alpha, IL-6, IL-1beta) and anti- (IL-4, TGF, IFN-gamma) inflammatory cytokines and MMP2 and 9 was quantified by real-time PCR, MMP proteins by Western analysis, and MMP activity by gel zymography. RESULTS: Chronic hypoxia increased (P < .05) TNF-alpha, IL-6, MMP2, and MMP9 mRNA levels but not IL-4, TGF, or IFN-gamma. Hypoxia increased protein levels of MMP9 but not MMP2, despite a hypoxia-induced increase in MMP2 activity. CONCLUSION: Intrauterine hypoxia may be an important stimulus in local generation of selected proinflammatory cytokines and MMPs in fetal hearts.

Chronic hypoxia differentially increases glutathione content and gamma-glutamyl cysteine synthetase expression in fetal guinea pig organs.

OBJECTIVE: Glutathione is a natural antioxidant in the fetus and adult. We sought to determine whether maternal hypoxia alters glutathione levels in fetal organs as an adaptive response to the reduced oxygenation. STUDY DESIGN: Timed pregnant guinea pigs were housed in either a Plexiglas chamber containing 10.5% O(2) from 46 to 60 days gestation (HPX, n=6) or in room air, as the normoxic control (NMX, n=5). Pregnant guinea pigs were anesthetized at near term ( approximately 60 days, term=65 days) and liver, lungand kidney were excised from anesthetized fetuses and stored frozen (-80 degrees C) prior to sample processing. Using the hypoxia marker, pimonidazole, we measured a hypoxia-induced increase in stained cells of fetal liver compared to no change in either the lung or kidney. To measure the effect of hypoxia among different organs, total glutathione (GSH) content and protein levels of gamma-glutamyl cysteine synthetase (gamma-GCS) were measured from the same organs. RESULTS: Maternal hypoxia increased (P<0.05) total glutathione levels by 121% in the fetal liver but had no effect in either fetal lung or kidney. Chronic hypoxia increased (P<0.05) gamma-GCS protein levels in all three fetal organs studied. CONCLUSION: These results demonstrate that the fetal response to maternal hypoxia may be organ specific. The increase in fetal liver glutathione via upregulation of gamma-GCS may be an important adaptive response to prolonged hypoxic stress.