Expressing breast milk or colostrum before a baby is born is known as antenatal expression or colostrum harvesting. This involves collecting the nutrient-rich “first milk” produced during the third trimester of pregnancy. The main concern is whether the stimulation could inadvertently cause labor to start prematurely. This technique is typically performed in the final weeks of pregnancy and is generally considered safe, provided a healthcare provider has given approval.
Understanding the Biological Response
The safety question centers on the body’s hormonal response to nipple stimulation. When the nipple is stimulated, the pituitary gland releases oxytocin. Oxytocin facilitates milk ejection and initiates uterine contractions during labor.
Oxytocin travels through the bloodstream and binds to receptors on the uterus, potentially causing contractions. These are often felt as harmless Braxton Hicks contractions. In a typical, low-risk pregnancy, the uterus is not sensitive enough to the small amounts of oxytocin released by gentle stimulation to trigger actual labor.
The concentration of oxytocin receptors increases significantly as pregnancy nears its end, making the uterus more responsive. Therefore, expression is typically delayed until a pregnancy is considered at term or near term. Any woman who experiences regular, painful, or persistent contractions should stop immediately and contact their healthcare provider.
Preparing for Postpartum Needs
Harvesting colostrum before birth provides a supply of milk immediately after delivery, especially if feeding challenges are anticipated. Colostrum is highly concentrated with antibodies and nutrients, helping to stabilize a newborn’s blood sugar and strengthen their immune system.
Antenatal expression is often recommended for specific medical or logistical reasons:
- Maternal diabetes (pre-existing or gestational), as infants are at increased risk of hypoglycemia (low blood sugar) shortly after birth. Stored colostrum allows staff to supplement the baby with human milk instead of formula to help regulate blood sugar levels.
- Anticipated separation from the baby, such as following a planned cesarean section or if the baby is expected to need care in the neonatal unit.
- A history of low milk supply with a previous baby.
- Infants with known conditions, like a cleft lip or palate, that might impede a successful early latch.
Situations Where Pumping is Not Recommended
While generally safe for low-risk pregnancies, antenatal expression is not advised in specific medical situations due to the increased risk of inducing preterm labor. These conditions heighten the uterus’s sensitivity to oxytocin, making even low levels of stimulation a concern.
Contraindications where the risk outweighs the potential benefits include:
- A history of preterm labor or birth in a previous pregnancy.
- Conditions involving the cervix, such as an incompetent cervix or the presence of a cervical suture.
- Any bleeding during the second or third trimester.
- Having a low-lying placenta (placenta previa).
- Being pregnant with multiples (twins or triplets).
- Preeclampsia, a high blood pressure disorder of pregnancy.
Techniques and Timing
Women who have received clearance should begin colostrum harvesting no earlier than 36 or 37 weeks of pregnancy. This timing minimizes the risk of stimulating preterm labor. It is important to begin the process slowly to monitor for any unusual uterine activity.
Hand expression is the preferred technique over using an electric breast pump. Colostrum is thick and produced in very small amounts, often just a few drops at a time. Pumps can waste this milk by causing it to stick to the parts; hand expression is gentler and allows for better collection.
The collected colostrum is typically drawn up into small, sterile syringes, labeled with the date and time of collection. These syringes should be frozen immediately and transported to the hospital in a cooler bag once labor begins. Expression should only be attempted for a short duration, such as 5 to 10 minutes per breast, one to two times daily.