This study evaluates the presence and quantity of non-caloric sweeteners in newborns umbilical cord blood, and in their mother's breast milk at delivery, at 2 months, 4 months and 6 months of age. Microbiota composition will be evaluated in milk and in feces of both mother and child.

The consumption of non-caloric sweeteners (ENC) is increasingly common in our country due to its wide use in all types of food and beverages, even those not labeled as "diet". Despite its widespread use and being an alternative to the consumption of sugars, several studies have shown that frequent ENC users are also at risk of excessive weight gain, type II diabetes, and cardiovascular diseases. In addition to this, the consumption of ENC in the early stages of life may predispose to the development of metabolic disorders later in life.The ENC have been shown to have effects on the health of those who consume them, causing metabolic disorders, weight gain and changes in the microbiota. The newborns, in whom gut microbiota is in the process of being established, influenced by the vaginal and intestinal microbiota of the mother, as well as by the mother's milk, are a vulnerable population in whom the effect of ENC consumption has not been investigated. This makes it relevant to study the prevalence of ENC in breast milk and umbilical cord blood of their newborns and to evaluate the composition of the intestinal and milk microbiota in order to identify changes attributable to the consumption of ENC.

Inclusion Criteria:

• Age 18-40 years old
• Women in labor
• Consent to participate in the study

Exclusion Criteria:

• Pre-term delivery (<30 weeks)
• Metabolic diseases (insulin resistance, diabetes, gestational diabetes)
• Hypertension
• Thyroid disease
• Cancer

Women in labor who come to the service of gynecology and obstetrics General Hospital Mexico. Usually, they are residents from Mexico City and metropolitan area (Mexico State).