This is a prospective cohort study that will be conducted in four low income countries to describe newborn weight patterns in the first month after birth and their association with clinical and demographic factors including dietary intake.

Background: Worldwide, more than 50 million children under 5 are wasted (weight-for-length/height Z-score (WLZ) <-2) and over 150 million children under 5 are stunted (length/height-for-age Z-score (LAZ) <-2); such wasting and stunting often begin during infancy. Optimal early nutrition can prevent wasting and stunting. In low income countries, there is therefore a need to understand early weight patterns and how they relate to dietary intakes.

Objectives: The proposed study will assess the relationship between infant dietary intake and weight change in low income countries by characterizing neonatal weight loss/gain patterns, dietary intake, and growth.

Methodology: We will use a prospective cohort study design to describe early infant weight patterns and their relationship to dietary intake. Up to 880 newborns and their mothers will be enrolled in four countries: Guinea-Bissau, Nepal, Pakistan and Uganda (up to 220 newborns/site). Enrolled infants will be followed from birth until one month of age and will be assessed by anthropometry, dietary survey and hemoglobin measurement. Mothers will also be assessed for anthropometry and hemoglobin. Infants' fathers and next-oldest siblings will also be enrolled for anthropometry if available and willing to participate.

Descriptive statistics will be used to describe sample characteristics. We will use various regression modeling techniques to examine the links between individual, family, and community characteristics and early infant weight patterns. Logistic regression models will also be used to consider potential confounding.

Study findings will allow us to describe weight patterns in the first 30 days after birth and their relationship to the dietary intake during that time. We hypothesize that infants who lose 6% or more of their birth weight prior to beginning weight gain will have lower WAZ at 30 days of age. We also hypothesize that at 12 days of age, weight change relative to birth weight will be lower for infants born <2500g then for infants born ≥2500g.

Inclusion Criteria:

• Birth weight ≥ 2000g.
• Mother ≥18 years of age and intends to breastfeed for at least 6 months.
• Mother anticipates availability for all study visits.

Exclusion Criteria:

• Birth weight <2000g
• Respiratory distress including tachypnea, head nodding, nasal flaring, chest retractions or grunting
• Known major congenital anomalies including orofacial clefts, neural tube defects and congenital heart defects
• Contraindication to breastfeeding at each site as determined by a site's national or sub-national health authorities
• Twins and other multiples.
• Newborns whose birth weight was not obtained in the first six hours.
• Newborns whose mothers intend to move or otherwise become unavailable during the follow up period of 30 days after birth

This study will enroll singleton, healthy newborns with birth weight ≥2000 g and their mothers. Fathers and next oldest siblings also will be enrolled if available and if any indicated assent/consent is able to be obtained.

Six months after completion of this multi-component project, unless otherwise agreed with the funder, we will make fully de-identified data from this study publicly available in a manner and under conditions agreed to by the funder, as required by the funder's Open Access Policy.

Six months after completion of the multi-component project which includes qualitative and quantitative assessment

Specified by the funder's Open Access Policy