https://orcid.org/0000-0003-1819-8273
Abstract
Background
The importance of nutrition in reproductive health is widely acknowledged with special emphasis given to periconceptional maternal diet and its implications on embryo-fetal development, pregnancy complications, and the health of the offspring.
Methods
Following the PRISMA guidelines, we searched for literature in PubMed, CINAHL, and WoS to gather newer information on how diet composition influences the concepts from the very early stages of pregnancy and how maternal health may be affected as well. Fifty-six studies published up to June 2020 met the inclusion criteria.
Results
With its proportioned and diversified macronutrient composition, the Mediterranean Diet prevents congenital anomalies, preterm birth, hypertensive disorders, and gestational diabetes. Similar dietary patterns rich in vegetables, nuts, fish, and cereals increase the likelihood of conception and have a protective action, mediated by their antioxidant properties, against orofacial clefts, congenital heart and limb defects in the progeny. Conversely, the pro-inflammatory features of western diets, rich in processed foods and low in fruit content, diminish fertility, increase miscarriage rates, and enhance the risk of neural tube defects regardless of folate supplementation.
Conclusions
It may be concluded that within the multiple dietary options, some of them are soundly associated with beneficial effects for the mother and the newborn.
An appropriate counseling must be offered to the woman of fertile age to make her aware of how periconceptional nutrition may help fulfill her reproductive expectations.
Implications for practice
Introduction
In recent years researchers have highlighted the correlation existing between maternal lifestyle during the periconceptional period and rates of relevant adverse reproductive outcomes (AROs) [Citation1].
Accordingly, inappropriate lifestyle factors like excessive food intake, reduced exercise, smoking, and alcohol consumption, have a recognized negative impact on reproductive health leading to higher rates of infertility and miscarriage, congenital malformations, preterm birth, and fetal growth impairment [Citation2].
Since habits are subject to change with time, they may be tackled with appropriate socio-sanitary interventions and in this setting maternal nutrition before and during gestation represents an innovative area of research in the perspective of reducing reproductive failures [Citation3].
Evidence already exists about the diet’s role in the periconceptional period and throughout pregnancy, modulating fetal development and growth. Maternal nutritional intake has a great impact on biological milestones like fetal programming, placental sensing, and fetal-maternal competition for nutrition. In addition, the quality of food affects embryonic development through biochemical signals within the uterine environment [Citation1]. Dietary patterns correlate with pregnancy complications as well, mainly gestational diabetes (GD) and hypertensive disorders (HD) [Citation4,5].
Animal and human studies also show that long-lasting epigenetic effects, to be expressed later in adult life, are linked to the early embryonic stages and the quality of maternal periconceptional food intake [Citation6–8]. A balanced diet may reduce non-communicable diseases (NCDs), namely neoplastic and cardiovascular disorders: confirmed patterns granting these benefits include the Mediterranean Diet (MD), the Fertility Diet (FD), and the Prudent Diet (PD) (Appendix A) [Citation9].
Dietary patterns represent a complex universe in which different food intakes challenge scientific research: assessing the relationship between single nutrients and risk of diseases may be complicated due to the nutrients interactions.
Thus, the search for protective or adverse associations has made progress and provided convincing results by addressing the general pattern of a diet rather than the intake of single substances or foods. This approach has been widely adopted to better assess diet quality and the related impact on maternal health and diseases of pregnancy.
The scope of our study is to provide a thorough analysis of the most recent findings related to the impact of maternal diet on fetal and maternal outcomes.
Methods
Data sources and searches
All human studies published up to June 2020, evaluating the association between periconceptional dietary patterns and reproductive outcomes were identified using PubMed, CINAHL, and Web of Science. Cross-matching references of the appraised papers ensured wider study capture. Words related to the following key concepts were combined using the Boolean operator “and” and “or” for the search: “periconceptional;” “maternal;” “diet” or “dietary patterns” or “nutrition;” and “maternal,” “fertility,” or “neonatal outcomes.” MeSH terms used include “Diet,” “Nutrients,” “Maternal Nutritional Physiological Phenomena,” and “pregnancy outcomes.”
Details of each mentioned specific diet are reported in Appendix A.
Study selection
Inclusion criteria were (a) intervention and observational studies, (b) nutritional maternal patterns around conception, (c) studies including fetal/maternal outcomes.
Exclusion criteria were (a) review articles, (b) animal studies, (c) no assessment of periconceptional exposures, (d) data on maternal food supplementation instead of dietary patterns, (e) undernourished populations in low-income countries, and (f) populations with specific nutritional needs (e.g. women suffering from chronic disease).
Data extraction and quality assessment
All potential publications were screened by three coauthors (C.B.S., C.M., and T.B.), who independently analyzed titles and abstracts to identify potentially eligible studies. The full text of selected papers was thoroughly examined, and suitable publications were included for data extraction. PRISMA Statements tools, i.e. “Checklist for Systematic reviews and Meta-Analysis items” and “Flow chart template,” were used to build the flow chart and to checklist essential items of the current review [Citation10].
Results
A total of 10,125 studies were identified and out of these, 103 were closely reviewed. The final selection included 56 cohort and case-control studies. A summary of the study selection process is displayed in .
Figure 1. Research of the literature flowchart (PRISMA).
In the three following sections, results of included studies, from across all continents, are presented.
Periconceptional outcomes ()
Recent studies indicate that periconceptional diets variably alter a woman’s fertility potential and likelihood to conceive. Adherence to the MD increases chances of clinical pregnancy and live birth after In Vitro Fertilization (IVF) or Intracytoplasmic Sperm Injection (ICSI) treatment [Citation11,12]; in addition, it reduces the number of infertility visits [Citation13].
Table 1. Dietary patterns and periconceptional outcomes: fertility.
Table 2. Dietary patterns and periconceptional outcomes: miscarriage.
Adhering to the Netherland Nutrition Center recommendations during 6 months before IVF/ICSI treatment also enhances chances of pregnancy. Just like the MD, this dietary pattern encourages daily consumption of large amounts of cereals, fresh vegetables, fruits, and vegetable oils, while maintaining between 1 and 2 portions of meat, legumes, or fish per week [Citation14].
A recent study on women suffering from anovulatory infertility reports an inverse correlation with adherence to the FD, body weight control, and physical activity [Citation15].
The impact of nutrition on fertility has been explored by studying the effects of the periconceptional intake of specific foods, instead of considering a complex dietary pattern: as a result of this approach, fish and cereals appear related to improved fertility [Citation16,17]. A subsequent study has confirmed the long assumed association between fish consumption and chances of live birth following infertility treatment [Citation18]. Research has also looked into the role of dairy products upon levels of anti-Mullerian hormone (AMH), a direct indicator of ovarian reserve: milk and fermented dairy consumption reduce the rate of AMH decline over time, with implications about their use to contrast infertility due to ovarian reserve loss [Citation19].
Fat-rich diets are generally associated with poor oocyte development, possibly related to oxidative stress in the follicular environment. Nevertheless, differentiating the fat types is critical to understand their impact on fertility: whereas high total fat (TFA) correlates with inflammation and insulin resistance- both causes of impaired ovulation-, ω-3 fatty acids may conversely improve fecundity by reducing anovulatory cycles, supporting endogenous progesterone output and increasing uterine blood flow [Citation20]. Longer time to pregnancy (TTP) and increased infertility were also registered in a large nulliparous population exposed to high fast food consumption with low fruit intake [Citation21].
The relationship between dietary patterns and IVF outcomes has seldom been examined in Asian and Middle East countries, where dietary habits and lifestyles greatly differ from western ones. A Japanese prospective cohort study has examined the association between periconceptional intake of vegetables and seafood, Western diets, and Rice and miso soup and IVF outcomes: after adjustment, no association was found between the three dietary patterns and clinical pregnancy rates [Citation22]. In contrast, a prospective cohort study carried out in Iran has provided evidence that a western type diet may adversely affect the chances of getting pregnant [Citation23].
Nutrition also plays an important role in the embryo’s early development and live births rates. In a large prospective cohort study, the pregnancy outcome of 15,959 pregnancies was assessed about three dietary patterns adherence (aMED, aHEI-2010, and FD) [Citation24]. Selected dietary patterns were suspected to reduce oxidative stress, improve endothelial function and enhance insulin sensitivity. The analysis of pregnancies occurring within one year after diet evaluation indicated that FD and fetal loss were inversely correlated when comparing women with the highest and lowest degrees of adherence.
An Iranian case-control study examined the Dietary Inflammatory Index (DII) and the incidence of miscarriage in women suffering from recurrent early pregnancy loss. The DII was calculated according to the dietary intake assessed by a validated and reproducible 168-item food-frequency questionnaire. Subjects with higher DII scores had an increased risk of miscarriage and abnormal levels of interleukin-6 [Citation25].
Maternal outcomes ()
Hypertensive disorders of pregnancy (HDP) and Gestational Diabetes Mellitus (GDM) are two maternal preventable complications affected by maternal diet.
Table 3. Dietary patterns and maternal outcomes: hypertensive disorders during pregnancy.
Table 4. Dietary patterns and maternal outcomes: gestational diabetes mellitus.
A large Australian study found a protective effect of MD with regards to HDP [Citation26] and similar conclusions are reported by other authors: diets rich in vegetables, fruits, grains, and nuts/beans/soya components are associated with a reduced risk of gestational hypertension and pre-eclampsia [Citation27–29]. Accordingly, a higher risk of pre-eclampsia is observed among women adopting western dietary patterns [Citation30].
In recent years, dietary Quality Scores (PDQS) have been developed to predict pregnancy complications related to maternal diet: a high-quality diet around conception reduces hypertensive disorders [Citation31,32]. A Canadian study concludes that large intakes of greens, fruits, oils, rice, fish, tomatoes, and pasta, are associated with the lowest odds of developing HDP [Citation33].
There is consensus that adhering to a healthy diet during pregnancy may help to prevent and controlling also GDM and in rare instances, diet does not seem tightly linked to GDM [Citation33].
Data from prospective cohort studies are consistent with the fact that consuming a diet rich in fruits, vegetables, lean meat/fish, and whole grains but low in hypercaloric poor food, is associated with a lower risk of excessive weight gain and GDM. A variety of dietary patterns decrease GDM risk, among them MD, the Dietary Approaches to Stop Hypertension (DASH), and the Healthy Eating Index (aHEI) [Citation28,Citation29,Citation34,Citation35]. Information related to periconceptional intake of legumes or starchy vegetables confirms that legumes decrease the risk of GDM but no association is reported for potatoes [Citation36].
A higher intake of animal proteins before pregnancy is significantly associated with a greater risk of GDM, whereas consuming proteins of vegetable origin protects against metabolic disorders [Citation37]. As shown in a Chinese study, consumption of animal proteins later in pregnancy leads to the same outcome, and the finding is relevant because of the higher prevalence of GDM in Asia compared to Europe and the US [Citation38].
In recent years, the prevailing dietary trend has been to reduce carbohydrates to obtain weight loss and to integrate with fat and proteins to satisfy the energy requirements. If applied to early phases of pregnancy, this diet carries different risks for GDM according to the type of protein sources: animal proteins and fats increase the likelihood of GDM, whereas no adverse effect is associated with protein and fat of vegetable origin [Citation39].
In the Nurses’ Health Study II, dietary quality scores (DQS) are associated with a lower risk of GDM, while dietary diversity scores (DDS) do not modify GDM prevalence. According to the authors, the DDS could be better exploited in low-resourced rather than in food-abundant settings. Thanks to its simple structure, the Prime Diet Quality Score is considered a promising index for measuring a sustainable, healthy diet on a global scale and it deserves a comprehensive evaluation of other nutritional recommendations, particularly in low- and middle-income countries [Citation32].
Further epidemiological research has explored the link between total meat consumption and the incidence of GDM during pregnancy. In the Spanish SUN Project, the effects of meat consumption and iron intake on GDM incidence have been assessed: high consumption of meat and of heme–iron is suspected to increase the risk of GDM [Citation40].
Several studies in Iran have been carried out focusing on the intake of different diets and nutrients during pregnancy: even though cultural roots greatly influence dietary patterns; fast food consumption has recently spread in the country. This new food habit, and especially the consumption of French fries, is associated with increased chances of GDM, even after adjusting for other determinants (e.g. BMI and physical activity) [Citation41]. Additional findings confirming the diabetogenic effect of a diet rich in processed food sound as a warning against the dangerous replacement of traditional foods with imported western ones [Citation42]. Partly reassuring are some new findings which compare three major dietary patterns during gestation – i.e. “western, traditional and healthy” – and find no specific association with GDM [Citation27], and the widespread opinion that western habits have not yet replaced the healthier local cultural dietary roots.
Fetal outcomes ()
The impact of single nutritional components on fetal and neonatal outcomes has been thoroughly analyzed. Among findings, children of women adhering to a diet rich in antioxidants contained in vegetables and fruits are less likely to suffer from congenital limb defects [Citation43]. Likewise, orofacial clefts rates in offspring inversely correlate with the maternal periconceptional intake of fruits and vegetables [Citation44].
Table 5. Dietary patterns and fetal outcomes: congenital defects.
Table 6. Dietary patterns and fetal outcomes: Fetal Growth.
Table 7. Dietary patterns and fetal outcomes: preterm birth.
A Dutch study comparing the Western and the Prudent Diets has found that children of women adopting the former nutritional pattern face a 2-fold risk of cleft lip regardless of folate supplementation [Citation45]. Similarly, high Diet Quality Indexes (DQI) or Mediterranean Diet Scores (MDS) in the year before conception are associated with a significant reduction in cleft lip/palate and neural tube defects, after excluding folic acid intake [Citation46]. Poor maternal adherence to the MD is associated with a 3- to 4-fold risk of spina bifida (SB) possibly related to increased oxidative stress secondary to vitamin B6, B12, and folates deficit [Citation47].
Adherence to the “One-carbon” diet, rich in fish and seafood, is associated with lower rates of congenital heart defects (CHD) [Citation48], and compliance to the PD decreases the risk of Fallot's tetralogy and septal heart defects [Citation49]. High quality of periconceptional nutrition, assessed using DQI and the MDS, reduces some major non-syndromic congenital heart diseases: conotruncal defects by 37%, Fallot's tetralogy by 24%, and overall atrial defects by 23% [Citation50].
In the US, gastroschisis is substantially more frequent in pregnant Latino adolescents, the reason for this association being still unclear: nutrition may be a major contributing factor since this age group often fails to comply with the usually recommended high-quality diet containing fruits, vegetables, whole grains and dairy [Citation51].
Maternal dietary patterns may also influence fetal growth. In the Omega study, a multicenter collaboration of US institutions, periconceptional intake of lean fish increased the risk of low birthweight (LBW) [Citation52].
Adherence to national nutritional guidelines, as affirmed by Norwegian and Australian researchers, may reduce risks of fetal weight abnormalities in both directions: LBW as well as macrosomia [Citation31,Citation53]. Elsewhere (Iran), results from other studies confirm the association between healthy dietary patterns during the first trimester and lower LBW rates [Citation30].
Among other diets, the MD prevents SGA newborns, with extra-virgin olive oil being the major contributing component in conjunction with selenium contained in vegetables and legumes [Citation28,Citation29,Citation54,Citation55].
Although fast-food consumption has long been identified as a poor dietary indicator with maternal diabetogenic effects, other findings make this correlation with fetal birthweight unlikely [Citation56]. The prevailing idea is that the fetal weight gain process depends on the appropriate balance of different macronutrients, mainly carbohydrates and proteins [Citation57,Citation58].
The same studies which explore the correlation between maternal diet and fetal growth have also looked into the effects of nutrition on Pre-term Birth (PTB) rates and have concluded that maternal compliance with a healthy periconceptional diet may prevent fetal prematurity [Citation28,Citation29,Citation31].
Adhering to a specific diet does not always bring the desired results which is the case reported by an Australian research group that finds no correlation between the government’s Recommended Food Score with premature birth [Citation53]. This discordancy may be partially explained by accounting for other aspects of periconceptional health and lifestyle that matter when it comes to preterm birth: maternal cultural habits, smoke, alcohol, and drug use, and other determinants of health [Citation56].
Discussion
Reproductive outcomes may be improved through social and health interventions targeting quality of nutrition, BMI control, physical exercise, smoke and alcohol consumption [Citation2]. Among these health determinants, maternal nutrition is fully recognized and plays a key role in pregnancy. Several studies focusing on the epigenetic field have concluded that an appropriate diet not only affects individuals’ health but impacts the well-being of future generations as well [Citation4,Citation5].
This review has included a large sample of studies focusing on the relationship between maternal nutrition and infertility. Special interest is placed on the outcome of assisted reproductive techniques (ART) associated with complex dietary patterns rather than with specific food components. To improve results of ART and increase the number of viable pregnancies, women should be encouraged to adhere to the MD or any equivalent food intake for which there is sound evidence of infertility consultations reduction, and a specifically higher likelihood of quality oocytes retrieval and successful implantation [Citation11,Citation14,Citation59].
Being characterized by an optimal ratio of macronutrients, the MD is rich in antioxidants counteracting the synthesis of reactive oxygen species (ROS) and the associated endometrial damage [Citation11]. Accordingly, there is consensus that women need to avoid pro-inflammatory diets to decrease the odds of miscarriage [Citation24,Citation25].
Despite these results, extendible to most geographical areas, there are settings with different dietary traditions where these findings are yet to be confirmed. In Japan, for instance, the implications of an MD or any related nutritional pattern upon IVF outcomes and clinical pregnancy rates remain undetermined [Citation22]. Paternal nutrition also needs to be accounted for since substantial data suggest that a healthy diet can improve semen quality and fecundability rates [Citation60].
Beyond the aforementioned fertility implications, the combination of foods and nutrients of the Mediterranean-style dietary pattern stands out with its’ protective action against HDP and GDM risk [Citation61].
Pregnancy challenges the woman’s metabolic balance, the result of pre-gestational insulin and β-cell function, and lifestyle factors including BMI. Adherence to a healthy diet prevents the metabolic deterioration that leads to GDM and lowers several induced risks which range from pre-eclampsia to induced labor which eventually increase perineal trauma and C-section rates [Citation40]. Late effects of GDM include developing type 2 diabetes in perimenopausal years and a higher risk of insulin resistance and obesity in the progeny [Citation34,Citation37].
When it comes to diet quality implications upon birth defects, research has traditionally considered a single nutritional factor at a time. Diet quality can indeed have a greater impact than individual nutrients, and this public health message needs to be implemented [Citation51]. A significant reduction of neural tube defects and oral-facial clefts risk has been observed with increasing diet quality. Abnormal limb formation may occur in the developing embryo and fetus due to ROS overproduction since oxidative stress may damage cell structures and reduce cell proliferation. By suppressing ROS and decreasing the number of free radicals, the MD counteracts the dysmorphic congenital process. However, more research is needed to investigate the mechanisms by which antioxidants act as protective agents against limb defects [Citation43].
Among pregnancy morbidities, intrauterine fetal growth has been widely studied due to its implications on post-natal development and adult life. Although non-dietary factors like smoking and HDP may impair fetal growth, maternal diet plays undoubtedly a unique role, linked, as it is, to obesity and GDM. Studies included in this review confirm the positive association between maternal periconceptional healthy dietary patterns (e.g. Mediterranean Diet) and an appropriate neonatal anthropometric development [Citation30,Citation31,Citation52,Citation54]. In SGA newborns, adverse events occur more frequently and include short-, medium- and long-term physical, psychological and social problems [Citation54].
Reduction of preterm birth is another valid reason for adopting a quality diet around conception: diet scores inversely correlate with preterm delivery, perinatal morbidity, and mortality, whereas they show a positive association with offspring’s long-term health and development [Citation31].
Conclusions
A varied and balanced diet is crucial for the well-being of any individual, from intrauterine life to adulthood and, when it comes to reproduction, maternal periconceptional nutrition plays a key role in preventing adverse outcomes. Acknowledging the need to improve dietary habits is a starting point to protect maternal and neonatal health.
Critical developmental processes of the embryo occur early in pregnancy and are greatly influenced by the woman’s nutritional status: dietary strategies, therefore, should be implemented much in advance before the start of pregnancy avoiding the otherwise inevitable delay and related effects.
Adherence to a healthy diet around conception protects against infertility, miscarriage, prematurity, birth defects, fetal growth restriction, GDM, and HDP. Educating women of childbearing age on the reproductive benefits of quality nutrition is crucial, and equally important is to encourage conscious nutritional behaviors in younger generations as an investment for their future health.
Disclosure statement
No potential conflict of interest was reported by the author(s).
References
- King JC. A summary of pathways or mechanisms linking preconception maternal nutrition with birth outcomes. J Nutr. 2016;146(7):1437S–1444S.
- Mastroiacovo P. La promozione della salute riproduttiva. Prospett Pediatr. 2012;42:243–252.
- Fontana R, Della Torre S. The deep correlation between energy metabolism and reproduction: a view on the effects of nutrition for women fertility. Nutrients. 2016;8(2):87.
- Stephenson J, Heslehurst N, Hall J, et al. Before the beginning: nutrition and lifestyle in the preconception period and its importance for future health. Lancet Lond Engl. 2018;391(10132):1830–1841.
- Fleming T, Watkins A, Velazquez M, et al. Origins of lifetime health around the time of conception: causes and consequences. Lancet. 2018;391(10132):1842–1852.
- Vohr BR, Poggi Davis E, Wanke CA, et al. Neurodevelopment: the impact of nutrition and inflammation during preconception and pregnancy in low-resource settings. Pediatrics. 2017;139(Suppl 1):S38–S49.
- Fleming TP, Watkins AJ, Sun C, et al. Do little embryos make big decisions? How maternal dietary protein restriction can permanently change an embryo's potential, affecting adult health. Reprod Fertil Dev. 2015;27(4):684–692.
- Lillycrop KA, Burdge GC. Maternal diet as a modifier of offspring epigenetics. J Dev Orig Health Dis. 2015;6(2):88–95.
- Sofi F, Macchi C, Abbate R, et al. Mediterranean diet and health status: an updated Meta-analysis and a proposal for a literature-based adherence score. Public Health Nutr. 2014;17(12):2769–2782.
- Moher D, Liberati A, Tetzlaff J, et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. J Clin Epidemiol. 2009;62(10):1006–1012.
- Karayiannis D, Kontogianni MD, Mendorou C, et al. Adherence to the Mediterranean diet and IVF success rate among non-obese women attempting fertility. Hum Reprod. 2018;33(3):494–502.
- Kermack AJ, Lowen P, Wellstead SJ, et al. Effect of a 6-week “Mediterranean” dietary intervention on in vitro human embryo development: the Preconception Dietary Supplements in Assisted Reproduction double-blinded randomized controlled trial. Fertil Steril. 2020;113(2):260–269.
- Toledo E, Lopez-del Burgo C, Ruiz-Zambrana A, et al. Dietary patterns and difficulty conceiving: a nested case-control study. Fertil Steril. 2011;96(5):1149–1153.
- Twigt JM, Bolhuis MEC, Steegers E, A P, et al. The preconception diet is associated with the chance of ongoing pregnancy in women undergoing IVF/ICSI treatment. Hum Reprod. 2012;27(8):2526–2531.
- Chavarro JE, Rich-Edwards JW, Rosner BA, et al. Diet and lifestyle in the prevention of ovulatory disorder infertility. Obstet Gynecol. 2007;110(5):1050–1058.
- Gaskins AJ, Chiu YH, Williams PL, et al. Maternal whole grain intake and outcomes of in vitro fertilization. Fertil Steril. 2016;105(6):1503–1510.e4.
- Gaskins AJ, Sundaram R, Buck Louis GM, et al. Seafood intake, sexual activity, and time to pregnancy. J Clin Endocrinol Metab. 2018;103(7):2680–2688.
- Nassan FL, Chiu Y-H, Vanegas JC, et al. Intake of protein-rich foods in relation to outcomes of infertility treatment with assisted reproductive technologies. Am J Clin Nutr. 2018;108(5):1104–1112.
- Moslehi N, Mirmiran P, Azizi F, et al. Do dietary intakes influence the rate of decline in anti-Mullerian hormone among eumenorrheic women? A population-based prospective investigation. Nutr J. 2019;18:83.
- Wise LA, Wesselink AK, Mikkelsen EM, et al. Dairy intake and fecundability in 2 preconception cohort studies. Am J Clin Nutr. 2017;105(1):100–110.
- Grieger JA, Grzeskowiak LE, Bianco-Miotto T, et al. Pre-pregnancy fast food and fruit intake is associated with time to pregnancy. Hum Reprod. 2018;33(6):1063–1070.
- Sugawa M, Okubo H, Sasaki S, et al. Lack of a meaningful association between dietary patterns and in vitro fertilization outcome among Japanese women. Reprod Med Biol. 2018;17(4):466–473.
- Jahangirifar M, Taebi M, Nasr-Esfahani M, et al. Dietary patterns and the outcomes of assisted reproductive techniques in women with primary infertility: a prospective cohort study. Int J Fertil Steril. 2019;2(4):316–323.
- Gaskins AJ, Rich-Edwards JW, Hauser R, et al. Prepregnancy dietary patterns and risk of pregnancy loss. Am J Clin Nutr. 2014;100(4):1166–1172.
- Vahid F, Shivappa N, Hekmatdoost A, et al. Association between maternal dietary inflammatory index (DII) and abortion in Iranian women and validation of DII with serum concentration of inflammatory factors: case-control study. Appl Physiol Nutr Metab. 2017;42(5):511–516.
- Schoenaker DAJM, Soedamah-Muthu SS, Callaway LK, et al. Prepregnancy dietary patterns and risk of developing hypertensive disorders of pregnancy: results from the Australian longitudinal study on Women's Health. Am J Clin Nutr. 2015;102(1):94–101.
- Hajianfar H, Esmaillzadeh A, Feizi A, et al. The association between major dietary patterns and pregnancy-related complications. Arch Iran Med. 2018;21(10):443–451.
- García de la Torre N, Assaf-Balut C, Jiménez Varas I, et al. Effectiveness of following mediterranean diet recommendations in the real world in the incidence of gestational diabetes mellitus (GDM) and adverse maternal-foetal outcomes: a prospective, universal, interventional study with a single group. The St Carlos study. Nutrients. 2019;11(6):1210.
- Assaf-Balut C, García de la Torre N, Fuentes M, et al. A high adherence to six food targets of the mediterranean diet in the late first trimester is associated with a reduction in the risk of materno-foetal outcomes: the St. Carlos gestational diabetes mellitus prevention study. Nutrients. 2018;11(1):66.
- Hajianfar H, Esmaillzadeh A, Feizi A, et al. Major maternal dietary patterns during early pregnancy and their association with neonatal anthropometric measurement. Biomed Res Int. 2018;2018:4692193.
- Hillesund ER, Bere E, Sagedal LR, et al. Pre-pregnancy and early pregnancy dietary behavior in relation to maternal and newborn health in the Norwegian fit for delivery study – a post hoc observational analysis. Food Nutr Res. 2018;62.
- Gicevic S, Gaskins AJ, Fung TT, et al. Evaluating pre-pregnancy dietary diversity vs. dietary quality scores as predictors of gestational diabetes and hypertensive disorders of pregnancy. PLOS One. 2018;13(4):e0195103.
- Jarman M, Mathe N, Ramazani F, et al. Dietary patterns prior to pregnancy and associations with pregnancy complications. Nutrients. 2018;10:914.
- Tobias DK, Zhang C, Chavarro J, et al. Prepregnancy adherence to dietary patterns and lower risk of gestational diabetes mellitus. Am J Clin Nutr. 2012;96(2):289–295.
- Van Horn L, Peaceman A, Kwasny M, et al. Dietary approaches to stop hypertension diet and activity to limit gestational weight: Maternal offspring metabolics family intervention trial, a technology enhanced randomized trial. Am J Prev Med. 2018;55(5):603–614.
- Goshtasebi A, Hosseinpour-Niazi S, Mirmiran P, et al. Pre-pregnancy consumption of starchy vegetables and legumes and risk of gestational diabetes mellitus among Tehranian women. Diabetes Res Clin Pract. 2018;139:131–138.
- Bao W, Bowers K, Tobias DK, et al. Prepregnancy dietary protein intake, major dietary protein sources, and the risk of gestational diabetes mellitus: a prospective cohort study. Diabetes Care. 2013;36(7):2001–2008.
- Liang Y, Gong Y, Zhang X, et al. Dietary protein intake, meat consumption, and dairy consumption in the year preceding pregnancy and during pregnancy and their associations with the risk of gestational diabetes mellitus: a prospective cohort study in southwest China. Front Endocrinol. 2018;9:596.
- Bao W, Bowers K, Tobias DK, et al. Prepregnancy low-carbohydrate dietary pattern and risk of gestational diabetes mellitus: a prospective cohort study1234. Am J Clin Nutr. 2014;99(6):1378–1384.
- Marí-Sanchis A, Díaz-Jurado G, Basterra-Gortari FJ, et al. Association between pre-pregnancy consumption of meat, iron intake, and the risk of gestational diabetes: the SUN project. Eur J Nutr. 2018;57:939–949.
- Lamyian M, Hosseinpour-Niazi S, Mirmiran P, et al. Pre-pregnancy fast food consumption is associated with gestational diabetes mellitus among Tehranian women. Nutrients. 2017;9:2018–2019.
- Sedaghat F, Akhoondan M, Ehteshami M, et al. Maternal dietary patterns and gestational diabetes risk: a Case-Control study. J Diabetes Res. 2017;2017:1–8.
- Pace ND, Desrosiers TA, Carmichael SL, et al. Antioxidant consumption is associated with decreased odds of congenital limb deficiencies. Paediatr Perinat Epidemiol. 2018;32(1):90–99.
- Krapels IPC, van Rooij IALM, Ocké MC, et al. Maternal nutritional status and the risk for orofacial cleft offspring in humans. J Nutr. 2004;134(11):3106–3113.
- Vujkovic M, Ocke MC, van der Spek PJ, et al. Maternal western dietary patterns and the risk of developing a cleft lip with or without a cleft palate. Obstet Gynecol. 2007;110(2):378–384.
- Carmichael SL, Yang W, Feldkamp ML, et al. Reduced risks of neural tube defects and orofacial clefts with higher diet quality. Arch Pediatr Adolesc Med. 2012;166(2):121–126.
- Vujkovic M, Steegers EA, Looman CW, et al. The maternal Mediterranean dietary pattern is associated with a reduced risk of spina bifida in the offspring. BJOG Int J Obstet Gynaecol. 2009;116(3):408–415.
- Obermann-Borst SA, Vujkovic M, de Vries JH, et al. A maternal dietary pattern characterised by fish and seafood in association with the risk of congenital heart defects in the offspring. BJOG Int J Obstet Gynaecol. 2011;118(10):1205–1215.
- Sotres-Alvarez D, Siega-Riz AM, Herring AH, et al. Maternal dietary patterns are associated with risk of neural tube and congenital heart defects. Am J Epidemiol. 2013;177(11):1279–1288.
- Botto LD, Krikov S, Carmichael SL, et al. Lower rate of selected congenital heart defects with better maternal diet quality: a population-based study. Arch Dis Child Fetal Neonatal Ed. 2016;101(1):F43–F49.
- Feldkamp ML, Krikov S, Botto LD, et al. Better diet quality before pregnancy is associated with reduced risk of gastroschisis in hispanic women. J Nutr. 2014;144(11):1781–1786.
- Mohanty AF, Thompson ML, Burbacher TM, et al. Periconceptional seafood intake and fetal growth. Paediatr Perinat Epidemiol. 2015;29(5):376–387.
- Gresham E, Collins CE, Mishra GD, et al. Diet quality before or during pregnancy and the relationship with pregnancy and birth outcomes: the Australian longitudinal study on Women's Health. Public Health Nutr. 2016;19(16):2975–2983.
- Martínez-Galiano JM, Olmedo-Requena R, Barrios-Rodríguez R, et al. Effect of adherence to a mediterranean diet and olive oil intake during pregnancy on risk of small for gestational age infants. Nutrients. 2018;10:1234.
- Martínez-Galiano JM, Amezcua-Prieto C, Salcedo-Bellido I, et al. Maternal dietary consumption of legumes, vegetables and fruit during pregnancy, does it protect against small for gestational age? BMC Pregnancy Childbirth. 2018;18(1):486.
- Moss JL, Harris KM. Impact of maternal and paternal preconception health on birth outcomes using prospective couples’ data in add health. Arch Gynecol Obstet. 2015;291(2):287–298.
- Cano-Ibáñez N, Martínez-Galiano JM, Amezcua-Prieto C, et al. Maternal dietary diversity and risk of small for gestational age newborn: findings from a case–control study. Clin Nutr. 2020;39(6):1943–1950.
- Sharma SS, Greenwood DC, Simpson NAB, et al. Is dietary macronutrient composition during pregnancy associated with offspring birth weight? An observational study. Br J Nutr. 2018;119(3):330–339.
- Vujkovic M, de Vries JH, Lindemans J, et al. The preconception Mediterranean dietary pattern in couples undergoing in vitro fertilization/intracytoplasmic sperm injection treatment increases the chance of pregnancy. Fertil Steril. 2010;94(6):2096–2101.
- Montagnoli C, Ruggeri S, Cinelli G, et al. Anything new about paternal contribution to reproductive outcomes? A review of the evidence. World J Mens Health. 2021;39:e1.
- Kibret KT, Chojenta C, Gresham E, et al. Maternal dietary patterns and risk of adverse pregnancy (hypertensive disorders of pregnancy and gestational diabetes mellitus) and birth (preterm birth and low birth weight) outcomes: a systematic review and meta-analysis. Public Health Nutr. 2019;22(3):506–520.