3.1 Lifestyle interventions during pregnancy may reduce the incidence of hypertensive disorders of pregnancy、gestational hypertension and preeclampsia
3.1.1 Lifestyle interventions during pregnancy can reduce the incidence of hypertensive disorders of pregnancy
Risk factors for hypertensive disorders of pregnancy include advanced age (age ≥35 years), obesity (preconception body mass index >28 kg/m2), excessive weight gain during pregnancy, nutritional deficiencies, family history (especially for mothers and sisters), and psychological factors (stress, negative emotions during pregnancy)[6, 9, 11]. Women with a history of hypertensive disorders of pregnancy (HDP), particularly gestational hypertension and preeclampsia, are more likely to develop hypertension, cerebrovascular disease, ischaemic heart disease, diabetes, hyperlipidemia, and chronic kidney disease later in life[45]. Studies have shown that dietary patterns high in vegetables, fruit, whole grains, nuts, legumes, fish, and vegetable oils, and lower in meat and refined grains can prevent hypertensive disorders of pregnancy[46].
The mechanism of preventing hypertensive disorders of pregnancy may be by controlling weight gain during pregnancy, improving neurological and endocrine function in pregnant women, reducing vascular resistance and blood viscosity, reducing oxidative stress, and improving endothelial cell function[9, 47-48],and it has also been suggested that exercise during pregnancy can promote placental growth and vascular development and prevent placental dysplasia [12, 47]. After appropriate aerobic exercise in women with hypertensive disorders of pregnancy, the activity of mitochondrial oxidative respiratory chain complex enzymes in the body was significantly improved, which could improve mitochondrial function and have a positive effect on the regulation of blood pressure levels[49].
Due to the inconsistency of interventions between studies, a subgroup analysis of hypertensive disorders of pregnancy showed that diet and exercise combined intervention and mindfulness/yoga group could reduce the incidence of hypertensive disorders of pregnancy, and the incidence of hypertension of pregnancy in the exercise intervention group was lower than that in the control group. This is similar to the conclusions of Davenport[9] et al.
3.1.2 Lifestyle interventions during pregnancy can reduce the incidence of gestational hypertension
During pregnancy Maternal nutrition gut microbiome composition, and metabolites derived from the gut microbiota are strongly associated with the development of hypertension in offspring. Large amounts of metabolites produced from different tryptophan metabolic pathways show both beneficial and harmful effects[50],the application of a healthy dietary pattern to women during pregnancy can reduce hypertensive disorders, while inadequate eating habits can affect women's health, worsening hypertensive disorders, leading to the birth of PE and small-for-gestational-age infants (SGA) [51]. low intake of fruits, green leafy vegetables, poultry and fish, Western dietary patterns (with high intake of red meat, processed meats, refined grain products, high fats and/ or high-sugar processed foods) may be associated with an increased risk of HDP and GDM[52]. Milk probiotics have also been found to be beneficial in at risk pregnant women[53], Sodium butyrate in drinking water may prevent maternal TF-induced hypertension in offspring by modulating the gut microbiota, its derived metabolites, and RAS [50]. The DASH diet is successful in reducing the risk of HDP [54].
Prenatal exercise can have a positive effect on overall cardiovascular risk profiles (eg, insulin resistance and GWG) during pregnancy[55] . Exercise interventions alone are effective in reducing the incidence of GDM, GH, and PE [9]. A study by Teede et al. showed that studies on the effectiveness of structured physical activity, including exercise in a specific training program under controlled conditions, significantly reduced the risk of gestational hypertension and preeclampsia[56] . Structured exercise is a reliable and safe strategy for maintaining optimal levels of blood pressure during pregnancy [57]. Yoga during pregnancy has been shown to reduce the incidence of hypertension, improve fetal maternal outcomes, and reduce cardiomyopathy risk in pregnant women at risk of growth hormone[58]. Dietary and lifestyle interventions during pregnancy have been clinically effective in reducing GWG, regardless of risk factors[59].
3.1.3 Lifestyle interventions during pregnancy can reduce the incidence of preeclampsia
High-fat or high-protein diets may cause oxidative stress by encouraging the production of homocysteine and other substances, aggravating vascular endothelial damage. Inadequate nutrition during pregnancy can have a direct impact on placental development and placental angiogenesis, leading to placental ischemia hypoperfusion, which is the recognized pathogenesis of preeclampsia. [60]. A lower risk of preeclampsia and premature birth may be linked to higher vitamin D concentrations during pregnancy [61]. Studies have found that women who score higher on healthful eating patterns have a lower chance of developing preeclampsia[62] ;low plasma folate and high homocysteine concentrations are particularly associated with the incidence of preeclampsia in early pregnancy. The women with the lowest folate contents and those who had the highest incidence of preeclampsia were more closely compared in both investigations.[63]. Undernutrition has been linked to a higher chance of developing preeclampsia in the preeclampsia pathophysiology, which may be caused by oxidative stress, inflammation, maternal endothelial dysfunction, and blood pressure [52].
Losing weight and lowering the mass of secreted active adipose tissue aren't the only benefits of exercise. Additionally, it fosters the ideal metabolic environment for the fetus' growth. Unfortunately, clinical research has not conclusively shown whether exercise significantly lowers the incidence of preeclampsia and gestational hypertension [64]. Physical activity during pregnancy studies has found that individuals who regularly engage in physical activity have a reduced risk of preform birth, preeclampsia, and gestational diabetes mellitus, and improved mental health [65].
The results of this study showed that lifestyle interventions during pregnancy could reduce the incidence of hypertensive disorders of pregnancy、gestational hypertension、preeclampsia and the difference was statistically significant (P<0.05), which was consistent with the results of Li Haiqiang [66] and others.
3.2 Lifestyle interventions during pregnancy can reduce the incidence of gestational diabetes mellitus, maternal cesarean scar rate and the incidence of macrosomia
3.2.1 Lifestyle interventions during pregnancy can reduce the incidence of gestational diabetes mellitus
Gestational diabetes mellitus (GDM) is one of the common metabolic complications of pregnancy and increases the risk of adverse pregnancy outcomes for the mother and her offspring [67]. Studies have shown that frequent consumption of potatoes, meat/processed meat, and animal-derived protein is associated with increased incidence of GDM [68], and that sweet and seafood patterns are independently associated with increased risk of GDM [69]; a dietary pattern of high vegetable, fruit, and rice intake is associated with a lower risk of GDM in Chinese pregnant women [70]. Meanwhile, a cross-sectional study by Yang Huixia et al [71] showed that increased physical activity during pregnancy was associated with a reduced risk of GDM in Chinese pregnant women.
Most of the current studies on lifestyle interventions during pregnancy have been conducted from the perspective of developing a nutritionally comprehensive and balanced diet plan, reasonably controlling the frequency and amount of diet, and guiding moderate exercise to limit energy intake and consumption during pregnancy under the premise of balanced nutrition, to improve insulin resistance and control gestational weight gain, to prevent gestational diabetes mellitus [66]. The results of this study showed that lifestyle interventions during pregnancy can reduce the incidence of gestational diabetes mellitus with a statistically significant difference, which is consistent with the findings of Koivusalo and Li Haiqiang [24,66].
Related studies [72] have shown that pregnant women with gestational diabetes mellitus have a higher incidence of macrosomia. Pregnant women with gestational diabetes are prone to complications such as macrosomia, fetal distress, gestational hypertension syndrome, abnormal fetal position, placenta praevia, placental abruption, and other indications for cesarean scar[73].
3.2.2 Lifestyle interventions during pregnancy can reduce the rate of maternal cesarean scar and the incidence of macrosomia
Cesarean scar has a greater risk to the mother and fetus, which can easily lead to maternal organ damage, intraoperative amniotic fluid embolism, scarred uterus, and unfavorable secondary delivery [74]; the fetus delivered by cesarean is prone to respiratory diseases such as asphyxia and wet lung [75]. Macrosomia are at higher risk of neonatal asphyxia, death, and brachial plexus injury during delivery and have a profound impact on the quality of neonatal survival [76], while mothers are often at high risk of prolonged labor, postpartum hemorrhage, and perineal trauma [77].
The amount of maternal weight gain is directly proportional to the incidence of macrosomia [78]. In addition, the large size of the newborn inevitably poses a great risk for vaginal delivery and increases the rate of cesarean scar, which is not only detrimental to the rapid postoperative recovery of the mother, but may also pose a major threat to her life and health [79]. During pregnancy, arranging a reasonable diet plan for pregnant women according to their physical condition at different times, adjusting their dietary structure, strengthening their nutritional guidance, and limiting their energy intake is of great practical significance in reducing the cesarean scar rate, preventing the appearance of huge babies, and improving the quality of pregnancy care [80]. Physical activity during pregnancy has beneficial effects on the health of both the mother and her fetus, including avoiding excessive maternal weight gain, maintaining fetal weight within normal limits, preventing pregnancy complications, and reducing the risk of macrosomia [81]. Exercise interventions during pregnancy have a significant improvement in the mode of delivery and the incidence of macrosomia (>4000 g) in pregnant women [82].
The results of this study showed that lifestyle interventions during pregnancy can reduce the incidence of cesarean scar and promote spontaneous delivery, which is consistent with the findings of Moufang Ji [83] et al. and Barakat [81].
3.3 The effect of lifestyle interventions during pregnancy on maternal week of delivery and the incidence of preterm infant is unclear
The results of this study showed that the difference between the gestational lifestyle intervention group and the control group was not statistically significant (P > 0.05) in terms of the incidence of the maternal gestational week of delivery, which is consistent with the findings of a study by Tu Feiyong [84]. In the study by Li J et al [85], the difference between the control group and the test group was not significant in terms of gestational weeks of delivery, but the study still concluded that lifestyle interventions during pregnancy are beneficial to fetal growth and that pregnant women should be encouraged to engage in appropriate activities during pregnancy. The relatively low prenatal risk factors and the relatively low incidence of adverse birth outcomes in most of the subjects in this study also made, the effect of gestational week of delivery not differ much, which also made most of the studies on gestational week of delivery not statistically significant.
Currently, interventions for pregnant women in various studies have focused on dietary modification, lifestyle, and exercise. In terms of the incidence of maternal preterm delivery, the difference between the gestational lifestyle intervention group and the control group was again not statistically significant according to Jin Y [86] (p > 0.05). Due to the inconsistency of interventions between studies, different lifestyle interventions such as exercise during pregnancy and dietary status have an impact on pregnancy outcomes. In terms of exercise during pregnancy, according to Li J [87] and Takami M [88] et al. and since physical exercise produces higher levels of epinephrine, norepinephrine,and catecholamines, this epinephrine and catecholamines may induce preterm labor through sarcoplasmic contraction and intrauterine growth restriction or induce sarcoplasmic relaxation depending on the action of receptors such as α1, α2 and β1 and β2 receptors, which increase the risk of preterm delivery. However, physical activity improves placental angiogenesis and reduces oxidative stress in pregnant women, both of which may reduce the risk of preterm delivery. In addition, lower levels of physical activity are associated with a reduced risk of preterm birth, but higher levels of physical activity are associated with an increased risk of preterm birth. Exercise during pregnancy may improve insulin sensitivity and reduce inflammation which may reduce the risk of preterm birth. Also according to Ferrara A [89] and Sun Xue [40], it was seen that the intervention on dietary status during pregnancy, although improved health behaviors and insulin resistance markers in women, while no group differences in perinatal complications were observed, which did not differ significantly between the intervention and usual care groups, but dietary nutrition is the main factor affecting maternal body mass index during pregnancy, and Individualized dietary guidance and nutritional management can effectively control weight gain during pregnancy, reduce the incidence of pregnancy complications and cesarean scar rate, and improve delivery outcomes. Therefore, the effect of lifestyle interventions during pregnancy on the gestational weeks of delivery and the incidence of preterm infant needs further validation.
3.4 Limitations of the present study
(i) Only published Chinese and English literature was included in this study, and there may be publication bias; (ii) The quality of the included literature was all B grade, some studies did not conduct allocation protocol concealment, and most of the literature was not blinded to implementers, participants or outcome measures, and there may be implementation and measurement bias; (iii) There were differences in interventions, intervention length,and frequency among the studies included in the Meta-analysis of this study, and The number and sample size of literature included in some subgroup analyses were small, which may affect the reliability of the study results. Therefore, the analysis results of this study need to be further validated, and more studies need to be conducted in the future to continue exploring the best measures to prevent hypertensive disorders of pregnancy and improve maternal and infant outcomes.