How do newborns gain weight?

From the Guidelines

Newborns gain weight primarily through adequate feeding, whether through breastfeeding or formula, with a recommended intake of 24 kcal/oz for newly born infants, increasing to 30 kcal/oz or more for infants nearing 1 year of age and toddlers. A healthy newborn should consume breast milk or formula every 2-3 hours, totaling 8-12 feedings per day. Breastfed babies typically need 1.5-3 ounces per feeding in the first week, increasing to 2-4 ounces by one month, while formula-fed infants may take 2-3 ounces per feeding initially, increasing to 3-4 ounces by one month 1. Proper latch for breastfeeding babies and correct formula preparation are essential. Newborns should gain approximately 5-7 ounces per week in the first few months, regaining their birth weight by 10-14 days of age. This weight gain occurs as their digestive systems develop and efficiently extract nutrients from milk, which provides the perfect balance of fats, proteins, carbohydrates, and other nutrients needed for rapid growth.

Some key points to consider for newborn weight gain include:

• Breastfeeding is the optimal form of infant feeding, and its growth pattern differs from that of formula-fed infants 1
• Healthy term neonates gain approximately 30 g per day until 3 months of age and 20 g per day between 3 and 6 months of age, typically doubling their birth weight by 4–6 months of age 1
• Iron requirements during early infant development are critical, and exclusively breastfed term neonates have extremely low dietary iron requirements during the first 6 months, determined to be approximately 0.27 mg/day 1
• Regular wet and soiled diapers (6-8 wet diapers and at least 3-4 stools daily after the first week) indicate adequate intake. If a baby isn't gaining weight appropriately, consulting a healthcare provider promptly is important to address any feeding issues or underlying medical concerns.

It's also important to note that factors such as maternal iron status, time of cord clamping, gestational age, birth weight, sex, and conditions that alter maternal-fetal iron exchange can influence neonatal iron stores at birth 1. Additionally, the use of fat or glucose to support the energy needs of infants with chronic lung disease of infancy (CLDI) remains the subject of investigation, with some studies suggesting that increased fat intake may help reduce CO2 production rate, although the benefits of increased dietary fat over the long term remain to be demonstrated 1.

Overall, adequate feeding and nutrition are crucial for newborn weight gain, and healthcare providers should closely monitor infants' growth and development to ensure they are receiving the necessary nutrients for optimal health.

From the Research

Newborn Weight Gain

Newborns gain weight through a combination of factors, including feeding patterns and overall health. The following points highlight the key aspects of newborn weight gain:

• Feeding patterns: Breastfeeding is the primary source of nutrition for newborns, and it plays a crucial role in their weight gain. Studies have shown that exclusively breastfed infants tend to have higher fat mass contents compared to exclusively formula-fed infants 2.
• Weight gain patterns: Formula-fed infants tend to gain weight and length more rapidly than breastfed infants from about 2 months of age to the end of the first year of life 3.
• Protein intake: The protein intake of formula-fed infants exceeds requirements after the first 1-2 months of life, which may contribute to differences in growth between breast- and formula-fed infants 3.
• Energy intake: Differences in energy intake may be responsible for differences in adiposity observed in older infants 3.
• Health outcomes: Exclusive breastfeeding until 6 months is associated with significantly higher weight, length, and lower probability of stunting, wasting, and infections in term infants 4.
• Complementary feeding: The introduction of complementary foods can affect newborn weight gain, and effectiveness trials of complementary feeding strategies in food-insecure countries are urgently needed 4.

Factors Affecting Newborn Weight Gain

Several factors can affect newborn weight gain, including:

• Method of feeding: Breastfeeding, formula feeding, or a combination of both can impact newborn weight gain 2, 5.
• Frequency and volume of feeding: The frequency and volume of feeding can affect newborn weight gain, with once-daily formula supplementation not altering growth through 180 days of age 5.
• Maternal health: Maternal health and nutrition can impact newborn weight gain, with exclusive breastfeeding for six months or more associated with delayed resumption of menses and more rapid postpartum weight loss in the mother 6.