Many nursing individuals wonder if their milk supply diminishes or “dries up” during pregnancy. This concern stems from the physiological changes the body undergoes. Understanding these processes clarifies expectations and informs decisions about continuing to nurse, as the body prioritizes the developing fetus, leading to noticeable shifts in lactation.
Hormonal Shifts and Supply Changes
Changes in milk supply during pregnancy involve a complex interplay of hormones. Elevated levels of progesterone and estrogen, produced by the placenta, counteract the effects of prolactin, the hormone responsible for milk synthesis. This hormonal competition reduces the volume of mature milk produced.
The mammary glands respond to these high pregnancy hormone levels by preparing for the new baby’s arrival, shifting their focus from mature milk production to developing nutrient-rich colostrum. This reorientation means that while some milk may still be present, it is often significantly less than pre-pregnancy levels, leading to the sensation of “drying up.”
For a nursing child, this decreased output can result in shorter feeding sessions or a perceived lack of milk. The taste and consistency of the milk may also alter due to the changing hormonal environment, which some toddlers might react to. These shifts are natural adaptations as the body prioritizes fetal development.
Milk Compositional Transformation
As pregnancy advances, the composition of breast milk undergoes a transformation, moving from mature milk to colostrum. This change typically begins around the second trimester, preparing the breasts for the newborn’s needs. Colostrum is often recognized as “first milk” due to its beneficial properties.
Colostrum is characterized by its high concentration of immunoglobulins, growth factors, and essential nutrients, making it suited for a new infant’s developing immune system and digestive tract. It provides passive immunity, protecting against pathogens and aiding a healthy gut microbiome. Its appearance often differs, being thicker and yellowish compared to mature milk.
Even if an older child continues to nurse, they will primarily receive these small amounts of colostrum rather than the larger volumes of mature milk previously available. The body’s shift to colostrum production ensures that the new baby receives this initial nourishment and immune support after birth.
Breastfeeding While Expecting
For individuals experiencing an uncomplicated, healthy pregnancy, continuing to breastfeed is considered safe for both parent and fetus. While nursing releases oxytocin, which can cause uterine contractions, these contractions are mild and not strong enough to induce labor in a healthy, full-term pregnancy. However, individuals with a history of preterm labor, bleeding, or other complications should seek medical advice.
Increased nipple sensitivity and tenderness during nursing sessions is common during pregnancy, often due to hormonal fluctuations. This discomfort might lead some to wean their older child. Maintaining adequate hydration and sufficient nutritional intake are also important, as the body supports both pregnancy and lactation simultaneously.
Healthcare providers can offer guidance regarding continued breastfeeding during pregnancy, especially with specific health concerns. Many healthy pregnancies allow for continued nursing, and after the new baby’s arrival, some choose to “tandem nurse” both children.
Post-Delivery Milk Resumption
Following the delivery of the placenta, a hormonal shift occurs, regardless of whether breastfeeding continued during pregnancy. The abrupt decline in progesterone levels, coupled with consistently high prolactin, triggers the onset of milk production, a process known as lactogenesis II or “milk coming in.” This commences within two to five days postpartum.
The breasts transition from producing small quantities of colostrum to generating a larger supply of mature milk. This change ensures the newborn receives ample nourishment. Those who nursed throughout pregnancy will also experience this increase in milk volume.
The body’s lactation system resets after birth, prepared to support the nutritional needs of the new infant. This allows for the option of tandem nursing, where both the newborn and an older child can be breastfed, with milk supply adjusting to accommodate demand.