The Chilean Maternal & Infant Cohort Study II (ChiMINCs II) is an ongoing cohort that is part of the Chilean Maternal and Infant Nutrition Observatory of the South-East area of Santiago, Chile. In total, 1927 pregnant women beneficiaries of the public health systems and their offspring were recruited before 12 weeks of gestation and are followed across pregnancy (<15, 26-28, and 35-37 weeks of gestation) and up to 2 years of age of their offspring. Two studies are currently nested in ChiMINCs II: 1) Breast Cancer Risk Assessment in Mothers (BRECAM) study, and 2) the ChiMINCs-COVID study. The primary objective of BRECAM study is to test the association between maternal metabolic indicators (i.e., insulin, glucose, IGF-1, and HbAc1 concentrations) at early pregnancy (i.e., <15 and 26-28 weeks of gestation) and breast density 3 months after the cessation of lactation. For this purpose, we collect maternal obstetric, lifestyle, dietary intake, anthropometric, and biochemical information. The aim of the ChiMINCs-COVID study is to assess dietary-related risks and mental health problems derived from the COVID-19 pandemic and their influence on maternal and infant's health and nutrition. Thus, we collected detailed information on dietary behaviors, mental health and COVID-related information at each trimester, along with neonatal and infant nutritional information. The purpose of the present work is to describe the design, methods, and descriptive information at recruitment of ChiMINCs-II, also discussing the implications that this study can have to better understand maternal and infant nutrition and health during the COVID-19 era.

Inclusion Criteria:

• 18 or more years of age
• Gestation <15 weeks at first prenatal visit
• No intention to move outside the city of Santiago in the next to years

Exclusion Criteria:

• High-risk pregnancy (i.e., preeclampsia, pre- existing diabetes)
• Pre-existing cancer or family history of breast cancer
• Intended to migrate from the public to the private health care system

Pregnant women

We identified pregnant women who received primary prenatal care within PHCC located in the South East area of Santiago. After, offspring of pregnant women were followed postnatally.

Data and blood samples that will be collected in this study will be under the custody of the principal investigator and a human subject protection review board will regulate its use. Others researchers may access the data by contacting to María Luisa Garmendia (Principal Investigator).