While the potential adverse outcomes of prenatal exposure to unhealthy lifestyle are well-established, little is known about the impact of these exposures in the reproductive and periconceptional periods. The associations between lifestyle behaviors and adverse pregnancy outcomes are highlighted.

Metabolism consists of all the chemical processes that occur in living cells. These processes/reactions can generally be classified as either anabolic (building) or catabolic (breaking down). General principles of metabolism are applied to the reproductive period and pregnancy.

Nutrition plays a major role in healthy pregnancy and development of the fetus. In addition, nutrition can expose humans to a wide range of potentially hazardous environmental constituents, such as organic pollutants and heavy metals from marine or agricultural food products while processing, producing and packaging.

Energy intake requirements in pregnancy match the demands of resting metabolism, physical activity and tissue growth. Energy balance in pregnancy is, therefore, defined as energy intake equal to energy expenditure plus energy storage. A detailed understanding of these components and their changes throughout gestation can inform energy intake recommendations for minimizing the risk of poor pregnancy outcomes.

Nutritional status during pregnancy can have a significant impact on maternal and neonatal health outcomes. Requirements for macronutrients such as energy and protein increase during pregnancy to maintain maternal homeostasis while supporting fetal growth. Certain micronutrients are also vital for improving pregnancy outcomes, including folic acid to prevent neural tube defects and iodine to prevent hypothyroidism.

Symptoms of discomfort due to pregnancy vary from woman to woman. Nausea, vomiting, fatigue, hemorrhoids, varicose veins, indigestion, bleeding gums, pica, fluid retention, backache, skin changes, stretch marks and constipation are the most reported. Dietary modifications can prevent or attenuate many of these. Common postpartum minor discomfort includes afterpains, perineal pain, constipation, urinary distention and lactation problems. Immediate and effective care during and after birth for these problems can ameliorate postpartum adaptation.

Women of reproductive age (WRA) are one of the groups most at risk of anemia, due to their physiological processes. There has been little progress in reducing the anemia burden among WRA over the past two decades, with prevalence actually increasing in some South Asian and sub-Saharan African countries. More recent estimates from WHO indicate that, globally, the prevalence of anemia among WRA has increased between 2011 and 2016, from 30% to 33%. The high global burden of anemia continues to underline the need for tailored approaches and target interventions on an individual basis.

Distinct biological functions of fat (e.g. fats as energy source or structural component), and the timing of exposure (e.g. fetal life, infancy or adulthood), determine related health outcomes. These outcomes can be suboptimal as a result of either too low or excessive fat intake. Total fat intake should comprise 20–35% of daily calories, similar to that for non-pregnant women. One of the most actively investigated research areas concerns the effects of polyunsaturated fatty acid intake during pregnancy and infancy in relation to a wide range of pregnancy and birth outcomes, infant neurodevelopment and various long-term outcomes.

Maintaining a healthy weight is crucial for fertility and pregnancy. Obesity can halve the success rate of assisted reproduction and raise miscarriage risk. Diet and exercise play fundamental roles in reproductive health and pregnancy. A balanced and nutrient-rich diet supports fertility and fetal development, while regular moderate exercise enhances cardiovascular health, reduces pregnancy complications and prepares the body for labor.

Deficiency or excess of micronutrients during pregnancy can have irreversible consequences for the newborn and child. If there is severe deficiency in at least one of the nutrients, depending on the length of deprivation, the child may have a decreased antioxidant defense, immune response, redox signaling, wound cicatrization and expression of regulator genes involved in the development of diseases. Iodine deficiency is found in all age groups, and lack of iodine leads to hypothyroidism and other disorders, classified as iodine deficiency disorders. Iodine supplementation can be recommended to fulfill individual needs, especially for expectant mothers, to avoid possible impacts that its deficiency can have on neural development of the fetus.

A strong body of evidence suggests that, if used early in pregnancy in women at high risk for gestational diabetes, inositols are able to significantly reduce the incidence of glucose metabolism alterations during pregnancy. Inositol acts as a mediator of the action of insulin, and it is necessary to activate key enzymes in the metabolism of glucose. Inositol‐ and antioxidant‐based supplements could then represent a valid therapeutic approach in pregnancy complicated by diabetes and by insulin resistance in order to improve glucose metabolism and delay or avoid insulin therapy when needed.

Obesity is a chronic, relapsing, progressive disease associated with severe complications and comorbidities. Adequate preconception counseling is important for women who are overweight or obese and are planning to become pregnant. Excess weight in the preconception period can influence fecundability (average per-cycle probability of conception), as well as the trajectory of metabolic changes during pregnancy and in the postpartum period due to inflammation, dyslipidemia and insulin resistance.

The current rationale for women fasting during labor is to protect them from pulmonary aspiration should general anesthesia be needed for an emergency operative delivery. However, prolonged fasting in labor has never been proved to influence the incidence of pulmonary aspiration, and some clinicians and midwives consider that preventing food intake can be detrimental to the mother, her baby and the progress of labor. Postnatal depression is a medical condition that affects many women and the development of their infants. There is a lack of evidence on treatment and prevention strategies that are safe for mothers and infants. Certain dietary deficiencies in a pregnant or postnatal woman's diet may cause postnatal depression.

Breastfeeding plays a crucial role in the health, growth and development of babies and has benefits for the mother too. Women may need some help to successfully feed their babies. They need support and reassurance as they learn this skill. Breastfeeding remains the superior form of infant nutrition and also serves as an extrauterine directive of immune development. The issues relevant to lactation success have changed as the world has changed. The ability to counsel breastfeeding women and a multiprong approach significantly impact her success, particularly in urban, low-income settings.

Adolescent, preconception and maternal nutrition represent a major public health issue that affects not only the health of adolescents and women, but also that of future generations. The FIGO recommendations aim to address several issues relating to nutrition in adolescent and young women before, during and after pregnancy.

Pregnancy is a critical period when nutrition and lifestyle choices significantly impact maternal and fetal health. Certain groups, such as adolescents, women with multiple pregnancy and those of advanced maternal age, face unique challenges and risks. However, these risks can be mitigated through proper nutrition and lifestyle interventions.