Once investigators have identified the pregnant women,they will ask for the pregnant women informed consent (adult) / written assent (adolescent) to obtain information about them since the eligibility criteria will be evaluated. These criteria are: age ≥15 years old, presence of obesity (IMC >28 for adolescents and >29 for adults), weeks of gestation (between 22 and 33 w), absence of chronic illnesses contraindicated for breastfeeding (HIV or AIDS, hepatitis, etc., except diabetes), not consuming drugs contraindicated during lactation, and in case of multiple pregnancies, there will be considered only the eldest child of twins (if there are more than two babies the pregnant women will be excluded from the study), absence of breast reduction surgery, and they may continue be living in Mexico City after delivery.