Maternal intermittent fasting during pregnancy induces fetal growth restriction and down-regulated placental system A amino acid transport in the rat

Effects of Intermittent Fasting on Female Reproductive Function: A Review of Animal and Human Studies

PURPOSE OF REVIEW

Intermittent fasting has gained significant attention, yet a comprehensive understanding of its impact on female reproductive health is lacking. This review aims to fill this gap by examining various intermittent fasting regimens and their effects on female reproductive function, along with potential mechanisms.

RECENT FINDINGS

In healthy non-overweight/obese or pregnant animal models, alternate-day fasting (ADF) and an 8-h time-restricted feeding (TRF) window may have adverse effects on reproductive function. However, these regimens show potential to mitigate negative consequences induced by a high-fat diet (HFD) or environmental exposure. A 10-h TRF demonstrates benefits in improving fertility in both normal-weight and HFD-fed animal models. In women with overweight/obesity or polycystic ovary syndrome (PCOS), the 5:2 diet and TRF significantly reduce the free androgen index while elevating sex hormone binding globulin, promising improvements in menstrual regulation. For pregnant Muslim women, available data do not strongly indicate adverse effects of Ramadan fasting on preterm delivery, but potential downsides to maternal weight gain, neonatal birthweight, and long-term offspring health need consideration. Factors linking intermittent fasting to female reproductive health include the circadian clock, gut microbiota, metabolic regulators, and modifiable lifestyles. Drawing definitive conclusions remains challenging in this evolving area. Nonetheless, our findings underscore the potential utility of intermittent fasting regimens as a therapeutic approach for addressing menstruation irregularities and infertility in women with obesity and PCOS. On the other hand, pregnant women should remain cognizant of potential risks associated with intermittent fasting practices.

Treatment of mice with maternal intermittent fasting to improve the fertilization rate and reproduction

Maternal intermittent fasting (MIF) can have significant effects on several tissue and organ systems of the body, but there is a lack of research on the effects on the reproductive system. So, the aim of our study was to analyze the effects of MIF on fertility. B6C3F1Crl (C57BL/6N × C3H/HeN) male and female mice were selected for the first part of the experiments and were analyzed for body weight and fat weight after administration of the MIF intervention, followed by analysis of sperm counts and activation and embryo numbers. Subsequently, two strains of mice, C57BL/6NCrl and BALB/cJRj, were selected and administered MIF to observe the presence or absence of vaginal plugs for the purposes of mating success, sperm and oocyte quality, pregnancy outcome, fertility status and in vitro fertilization (IVF). Our results showed a significant reduction in body weight and fat content in mice receiving MIF intervention in B6C3F1Crl mice. Comparing the reproduction of the two strains of mice. However, the number of litters was increased in all MIF interventions in C57BL/6NCrl, but not statistically significant. In BALB/cJRj, there was a significant increase in the number of pregnant females as well as litter size in the MIF treatment group, as well as vaginal plugs, and IVF. There was also an increase in sperm activation and embryo number and the MIF intervention significantly increased sperm count and activation. Our results suggest that MIF interventions may be beneficial for reproduction in mice.

Treadmill Exercise Reverses the Adverse Effects of Intermittent Fasting on Behavior and Cortical Spreading Depression in Young Rats

Intermittent fasting (IF) and physical exercise (PE) have beneficial psychological and physiological effects, improving memory and anxiety-like behavior. However, the impact of this combination on brain electrophysiological patterns is unknown. We aimed to evaluate the behavior and parameters of a brain excitability-related phenomenon named cortical spreading depression (CSD) in young rats (31-87 days of life) submitted to IF and treadmill PE for eight weeks. Sixty-four male and female Wistar rats aged 24 days were randomized into control, IF, PE, and IF+PE groups. Behavioral tests (open field (OF), object recognition, and elevated plus maze (EPM)) were performed, and the CSD propagation features were recorded. IF caused behavioral responses indicative of anxiety (lower number of entries and time spent in the OF center and EPM open arms). IF also reduced the discrimination index for object recognition memory tests and increased the propagation velocity of CSD. PE rats displayed more entries into the OF center and lowered CSD propagation speed. Data suggest that IF worsens anxiety-like behavior and memory and accelerates CSD in young rats. In contrast, PE reverted the unfavorable effects of IF. The brain effects of IF and PE at younger ages are recommended for study.

Dousing the flame: reviewing the mechanisms of inflammatory programming during stress-induced intrauterine growth restriction and the potential for ω-3 polyunsaturated fatty acid intervention

Intrauterine growth restriction (IUGR) arises when maternal stressors coincide with peak placental development, leading to placental insufficiency. When the expanding nutrient demands of the growing fetus subsequently exceed the capacity of the stunted placenta, fetal hypoxemia and hypoglycemia result. Poor fetal nutrient status stimulates greater release of inflammatory cytokines and catecholamines, which in turn lead to thrifty growth and metabolic programming that benefits fetal survival but is maladaptive after birth. Specifically, some IUGR fetal tissues develop enriched expression of inflammatory cytokine receptors and other signaling cascade components, which increases inflammatory sensitivity even when circulating inflammatory cytokines are no longer elevated after birth. Recent evidence indicates that greater inflammatory tone contributes to deficits in skeletal muscle growth and metabolism that are characteristic of IUGR offspring. These deficits underlie the metabolic dysfunction that markedly increases risk for metabolic diseases in IUGR-born individuals. The same programming mechanisms yield reduced metabolic efficiency, poor body composition, and inferior carcass quality in IUGR-born livestock. The ω-3 polyunsaturated fatty acids (PUFA) are diet-derived nutraceuticals with anti-inflammatory effects that have been used to improve conditions of chronic systemic inflammation, including intrauterine stress. In this review, we highlight the role of sustained systemic inflammation in the development of IUGR pathologies. We then discuss the potential for ω-3 PUFA supplementation to improve inflammation-mediated growth and metabolic deficits in IUGR offspring, along with potential barriers that must be considered when developing a supplementation strategy.

Maternal intermittent fasting deteriorates offspring metabolism via suppression of hepatic mTORC1 signaling

The metabolic benefits of intermittent fasting (IF) have been well recognized. However, limited studies have examined the relationship between long-term maternal IF before pregnancy and offspring health. In this study, a C57BL/6J mouse model of long-term IF before pregnancy was established: 4-week-old female mice were subjected to alternate-day fasting for 12 weeks and resumed normal diet after mating. Female mice in the control group were fed ad libitum. Offspring mice were weaned at 6 weeks of age and fed a normal chow diet or a 60% high-fat diet. The effects of long-term pre-pregnancy IF on offspring metabolism and its underlying mechanism were examined. We found that neonatal IF offspring weighted significantly less relevant to control mice. This difference gradually disappeared as a result of catch-up growth. In the IF offspring, adipose tissue mass was significantly increased. This alteration was associated with a considerable deterioration in glucose tolerance. No significant difference in food intake was observed. Further, lipid deposition as well as triglyceride contents in the liver were greatly increased. Maternal IF significantly decreased levels of DNA methyltransferase in the liver of offspring. DNA methylation modifications of molecules associated with the mTORC1 signaling pathway were significantly altered, leading to the significant inhibition of mTORC1 signaling. Overexpression of S6K1 activated hepatic mTORC1 signaling and reversed the metabolic dysfunction in IF offspring. In conclusion, long-term pre-pregnancy IF increases hepatic steatosis and adiposity, as well as impairs glucose metabolism in adult offspring. This occurs through DNA methylation-dependent suppression of hepatic mTORC1 signaling activity.

Intermittent fasting and immunomodulatory effects: A systematic review

Introduction

strategy of periodic food restriction and fixed eating windows, could beneficially modify individuals by losing body weight, regulating glucose or lipid metabolism, reducing blood pressure, and modulating the immune system. Specific effects of IF and its mechanisms have not yet been assessed collectively. Thus, this systematic review aims to summarize and compare clinical trials that explored the immunomodulatory effects of IF.

Methods

After screening, 28 studies were included in this systematic review.

Results

In addition to weight loss, IF could benefit health subjects by strengthening their circadian rhythms, migrating immune cells, lower inflammatory factors, and enriching microbials. In addition of the anti-inflammatory effect by regulating macrophages, protection against oxidative stress with hormone secretion and oxidative-related gene expression plays a key beneficial role for the influence of IF on obese subjects.

Discussion

Physiological stress by surgery and pathophysiological disorders by endocrine diseases may be partly eased with IF. Moreover, IF might be used to treat anxiety and cognitive disorders with its cellular, metabolic and circadian mechanisms. Finally, the specific effects of IF and the mechanisms pertaining to immune system in these conditions require additional studies.

Impact of maternal intermittent fasting during pregnancy on cardiovascular, metabolic and renal function in adult rat offspring

Pregnant Muslim women are exempt from fasting during Ramadan; however a majority are reported to fast. The impact of this form of maternal intermittent fasting (IF) on fetal development and offspring health is not well defined. Using a rat model, we have shown previously that maternal IF results in fetal growth restriction accompanied by changes in placental nutrient transport function. The aim of this study was to assess cardiovascular, metabolic and renal function in adult offspring of IF-exposed dams. Food was withheld from Wistar rats from 17:00 to 09:00 daily throughout pregnancy; controls had ad libitum access to food. Birth weight was unaffected; however male IF pups grew more slowly up to 10 weeks of age (P < 0.01) whereas IF females matched their control counterparts. Systolic blood pressure (SBP), glucose tolerance and basal renal function at 14 weeks were not affected by IF exposure. When offered saline solutions (0.9–2.1%) to drink, females showed a greater salt preference than males (P < 0.01); however there were no differences between dietary groups. A separate group of pups was weaned onto a 4% NaCl diet. SBP increased in IF pups sooner, at 7 weeks (P < 0.01), than controls which became hypertensive from 10 weeks. Renal function did not appear to differ; however markers of renal injury were elevated in IF males (P < 0.05). Maternal IF does not affect resting cardiovascular, metabolic and renal function; but when challenged by dietary salt load male IF offspring are more prone to renal injury.

Correlation between Parturients' Uterine Artery Blood Flow Spectra in the First and Second Trimesters of Pregnancy and Fetal Growth Restriction

Objective

To explore the correlation between parturients' uterine artery blood flow spectra in the first and second trimesters of pregnancy and fetal growth restriction (FGR).

Methods

The data of parturients treated in our hospital from February 2018 to February 2020 were retrospectively analyzed, 50 parturients with FGR were selected as the FGR group, and other 50 healthy cases were selected as the control group. In the first trimester (11-12 weeks of gestation) and the second trimester of pregnancy (13–24 weeks of gestation), the parturients of the two groups accepted the color Doppler ultrasonography (CDS), their hemodynamics indicators of uterine artery were recorded, and the correlation between their uterine artery blood flow spectra in the two periods and FGR was analyzed with the Receiver Operating Characteristic (ROC) curve.

Results

No statistical differences in the parturients' general information including age, gestational weeks, gravidity, and parity between the two groups were observed (P > 0.05); the newborn's body weight, Apgar scores, number of preterm infants, and the number of infants transferring to the neonatal intensive care unit (NICU) were significantly different between the two groups (P < 0.05); in the first and second trimesters of pregnancy, the uterine artery pulsatility index (UtA-PI), uterine artery resistance index (UtA-RI), maximal systolic flow velocity, and systolic/diastolic (UtA-S/D) ratio were significantly higher in the FGR group than in the control group (P < 0.05), and the time-averaged maximal velocity (TAMX) was significantly lower in the FGR group than in the control group (P < 0.001); in early pregnancy, the incidence of early diastolic notch at bilateral uterine arteries between the two groups was not significantly different (P > 0.05), and the unilateral and total incidence in the first trimester as well as the unilateral, bilateral, and total incidence in the second trimester were significantly higher in the FGR group than in the control group (P < 0.05); in the first trimester, the sensitivity of detecting FGR with a uterine artery blood flow spectrum was 0.820, AUC (95% CI) = 0.840 (0.757–0.923), and in the second trimester, it was 0.860, AUC (95% CI) = 0.900 (0.832–0.968).

Conclusion

There is a correlation between uterine artery blood flow spectra in the first and second trimesters of pregnancy and FGR, and the sensitivity of spectrum in the first trimester is higher than that in the second trimester, presenting a better clinical application value.

Maternal intermittent fasting during pregnancy: a translational research challenge for an important clinical scenario

In volume 135, issue 11 of Clinical Science, Alkhalefah et al. report that, in pregnant rats, repeated, cyclic fasting, mimicking the fasting experienced by observant Muslim pregnant women during Ramadan, alters placental amino acid transport and increases the incidence of low birth weight. Though Muslim women are exempt, many observe Ramadan: >500 million fetuses worldwide may be exposed to Ramadan fasting in each generation, and low birth weight increases the risk of developing chronic disease in the future adult. Several mechanisms, including altered circadian rhythm, maternal stress, undernutrition or compensatory overeating at the breaking of fast, could, in theory, impact fetal growth during Ramadan. Limitations of the experimental model obviously prevent direct extrapolation to humans. Whether Ramadan fasting indeed affect fetal growth therefore remains unclear, as there is no clear-cut evidence from epidemiological studies. The paper illustrates the need to design further case-controlled studies in large cohorts of women who fasted at various stages of pregnancy, compared to appropriately matched women who did not fast, as well as more experimental studies focused on this issue of public health relevance.