Lactation begins during pregnancy and rapidly evolves in the first week after birth. This initial period establishes the milk supply, which adapts to meet the newborn’s needs. Understanding these changes helps parents feel confident about their baby’s nourishment. The first seven days involve a swift shift in the type and volume of milk produced, moving from primarily hormonal control to a system based on demand and removal.
The Transition from Colostrum to Mature Milk
The process of milk production, known as lactogenesis, occurs in distinct stages. The first week encompasses the shift from Stage I to Stage II. Lactogenesis I begins before birth, resulting in colostrum, the initial milk. Colostrum is present in small volumes and is characterized by its thick, yellowish color and highly concentrated composition of antibodies and nutrients.
Lactogenesis II, often described as the milk “coming in,” typically starts around the third to fifth day postpartum. This transition is triggered by the rapid drop in the hormone progesterone following the delivery of the placenta. This hormonal change allows prolactin to stimulate the onset of copious milk secretion. This shift brings about a noticeable increase in milk volume and a change from colostrum to transitional milk.
The physical sensation of the milk volume increasing may manifest as breast fullness or engorgement around days three to five. The transitional milk produced during this stage is higher in fat and lactose, supporting the baby’s rapid growth and energy requirements.
Quantitative Expectations at Seven Days Postpartum
By seven days postpartum, the milk supply is developing quickly to meet the newborn’s growing needs. While production volumes vary widely, the total expected daily milk production often falls in the range of approximately 500 to 750 milliliters, which is about 18 to 25 ounces per 24 hours. This volume aligns with the newborn’s stomach capacity, which has grown to approximately 45 to 60 milliliters (1.5 to 2 ounces) per feeding.
This period marks a fundamental shift in the control of milk production. Initially, the process is largely controlled by hormones (endocrine control), ensuring some milk production regardless of feeding frequency. By the end of the first week, the system transitions to a local supply-and-demand mechanism (autocrine control). This means that the amount of milk removed from the breasts directly influences the amount produced.
The total daily output is a more accurate measure of supply than the amount expressed during a single session. For those expressing milk, an output of about one to two ounces from both breasts combined per pumping session is considered a common range at this stage. Pumping output does not always reflect the baby’s actual intake, as a baby is often more efficient than a pump at removing milk.
Indicators of Adequate Infant Intake
Since parents cannot precisely measure the volume a baby drinks during a feeding, the most reliable way to assess adequate intake is by observing the baby’s output and behavior. By one week postpartum, the baby should be showing definite signs of receiving sufficient milk. Stools should have transitioned from the dark, tarry meconium to a loose, yellow, seedy consistency.
A well-nourished one-week-old baby should have at least three to four bowel movements per 24 hours, each about the size of a dollar coin or larger. Wet diaper count is another objective measure, with a minimum of six heavy, wet diapers expected every 24 hours. The urine in these diapers should be pale yellow or colorless, indicating good hydration.
Weight gain is the ultimate indicator of adequate milk transfer, following the initial physiological weight loss after birth. While a newborn may lose up to 8 to 10 percent of their birth weight, they should be gaining weight by the end of the first week. During feedings, parents should observe the baby starting with rapid sucks followed by long, rhythmic swallows, often accompanied by a distinct audible “kah” sound. The baby should also appear content and satisfied after most feeds, with the breasts feeling noticeably softer.
Maximizing and Sustaining Milk Supply
The principle of supply and demand is the foundation for maximizing and sustaining milk production at one week postpartum. Frequent and effective removal of milk is the primary driver for establishing a full supply. This means feeding the baby whenever hunger cues are observed, which typically translates to at least eight to twelve times in a 24-hour period.
Ensuring a deep and comfortable latch is crucial, as poor milk transfer is a common cause of low supply. The baby’s chin should touch the breast, and the mouth should be wide, taking in a large amount of the areola. If the baby is not feeding directly, expressing milk at least eight times a day is necessary to mimic the baby’s frequent feeding pattern.
For those who need to express, double pumping both breasts simultaneously can increase the volume of milk collected and help build a stronger supply. Furthermore, incorporating self-care, such as maintaining adequate hydration and eating a nutrient-dense diet, supports the body’s demanding work of producing milk. Avoiding stress and prioritizing rest, even in short periods, can also positively influence the milk-producing hormones.