Colostrum is the first milk produced by the mammary glands, serving as the initial nourishment for a newborn. It is often referred to as “liquid gold” because of its rich, golden color and dense concentration of beneficial components. This early milk promotes the newborn’s growth and development while fighting against pathogens. It establishes the baby’s first line of immune defense.
Color, Consistency, and Volume
The appearance of colostrum can vary significantly, but it is most commonly a deep, rich yellow or orange hue. This striking color is a direct result of the high concentration of beta-carotene. Beta-carotene is an antioxidant and a precursor to Vitamin A, supporting the baby’s vision, skin, and immune function. Colostrum may also appear creamy white, or even clear and watery, which are all considered normal variations.
The consistency of this first milk is noticeably thicker and often stickier than the mature milk that follows. This dense texture occurs because colostrum has a higher proportion of proteins and a lower content of fat and lactose, making it highly concentrated. The volume produced is small, perfectly matching the size of a newborn’s stomach.
A baby typically consumes only about 5 to 7 milliliters (about one to one and a half teaspoons) of colostrum per feeding during the first 24 hours of life. The total daily production volume in the first few days is usually around 30 milliliters, or about one ounce. This small, highly concentrated quantity ensures the baby receives maximum nutritional benefit without overwhelming their developing digestive system.
The Short Window of Colostrum Production
Colostrum production begins well before birth, with lactogenesis (milk production) starting as early as the second trimester of pregnancy. This initial phase, known as lactogenesis I, involves the mammary glands preparing to secrete milk, though the hormone progesterone keeps the volume low. The true shift in milk production is triggered by the delivery of the placenta, which causes a rapid drop in progesterone levels.
This hormonal change initiates lactogenesis II, often described as the milk “coming in,” which typically occurs between two to five days postpartum. During this brief window, the body transitions from producing low-volume, highly concentrated colostrum to higher-volume transitional milk. The duration of colostrum production is short, lasting only the first few days after birth.
Transitional milk continues to change over the next one to two weeks, gradually increasing in volume and changing composition. This transitional phase eventually leads to the production of mature milk, which is sustained for the remainder of the feeding period. The short period of colostrum production highlights its temporary and specialized role in the newborn’s first days of life.
Why It Looks Different: The Nutritional Makeup
The appearance of colostrum is a direct reflection of its dense nutritional composition. Its deep color is a visual indicator of the high level of protective components, such as beta-carotene. Compared to mature milk, colostrum contains approximately two times the amount of protein and four times the amount of zinc.
A large part of this concentrated makeup is the high density of immune factors, which are responsible for its thick consistency. It is rich in immunoglobulins, particularly secretory Immunoglobulin A (IgA), the dominant immune component in human colostrum. These immunoglobulins coat the lining of the baby’s intestines, providing a protective barrier against germs and infections.
Colostrum is also packed with white blood cells (leukocytes) that actively fight infection and inflammation. Its composition, which is lower in fat and sugar, makes it easier for the newborn to digest. Furthermore, its laxative properties help the baby pass meconium, the first dark stool.