Antenatal expression, or colostrum harvesting, is the practice of gently hand-expressing the first form of breast milk before the baby is born. Colostrum, often called “liquid gold,” is nutrient-dense, rich in antibodies, and naturally produced starting around the second trimester. The question of beginning this practice specifically at 37 weeks gestation is common because this timing marks the start of the full-term period. Deciding to express colostrum before delivery is a medical decision that should always be made in consultation with a healthcare provider to ensure the safety of both the parent and the baby.
Understanding the Safety Risks of Pumping at 37 Weeks
The primary concern regarding nipple stimulation during pregnancy is its potential to trigger uterine contractions and inadvertently induce labor. This physiological response is due to the release of oxytocin, a hormone produced when the nipple is stimulated. Oxytocin causes the smooth muscles of the uterus to contract.
While 37 weeks is considered the threshold for a full-term pregnancy, unnecessary uterine stimulation should still be approached with caution. The risk of inducing labor is low in a healthy, low-risk pregnancy, but if uterine tightening or cramping is felt during expression, the activity must be stopped immediately.
Medical professionals recommend hand expression over using an electric breast pump during the antenatal period. Hand expression is a gentler method of stimulation that is less likely to cause a strong oxytocin surge. Using a pump before delivery is generally not advised unless directed by a medical provider.
The focus is collecting small, concentrated drops of colostrum, which hand expression handles more effectively. Starting at 37 weeks balances maximizing collected colostrum with minimizing the risk of stimulating contractions.
Why Antenatal Expression is Medically Recommended
A healthcare provider may recommend starting antenatal colostrum expression at 37 weeks to ensure the newborn receives this initial, beneficial milk. This recommendation is typically reserved for situations where the baby is at risk of hypoglycemia, or low blood sugar, immediately after birth. The most common reason is a parent having pre-existing diabetes or Gestational Diabetes Mellitus (GDM).
Colostrum is high in energy and helps stabilize a newborn’s blood glucose levels. A stored supply prevents the need for formula supplementation if the baby struggles to latch or mature milk is delayed.
Antenatal expression is also valuable when a parent anticipates separation from the infant after delivery, such as a planned Cesarean section or likely Neonatal Intensive Care Unit (NICU) admission. In these scenarios, collected colostrum can be the baby’s first food, ensuring they receive immunological and nutritional benefits even if direct feeding is not possible.
Other circumstances prompting a recommendation include a known history of low milk supply or the presence of flat or inverted nipples, which can make early latching difficult. Collecting colostrum beforehand provides a nutritional bridge and allows the parent to practice the expression technique, building confidence before the baby’s arrival.
Step-by-Step Guide for Colostrum Harvesting
Once medical clearance is obtained, colostrum harvesting is best performed using hand expression, as electric pumps are not effective for the initial thick, sticky drops. Begin by ensuring your hands are thoroughly washed and you are in a comfortable, relaxed position.
Hand Expression Technique
- Gently massage the entire breast using a light, circular motion from the outer edges inward toward the areola for a few minutes. This stimulates the milk ejection reflex.
- Place your thumb above the areola and your index finger below it, forming a “C” shape a few centimeters back from the nipple.
- Gently press your fingers straight back toward the chest wall, then compress the thumb and forefinger together, rolling them slightly forward without dragging the skin.
- Avoid pinching the nipple itself, as this can cause discomfort and inhibit flow.
- Collect the concentrated drops of colostrum directly into a sterile, blunt-tipped syringe, typically 1 to 5 milliliters in size.
A typical session involves expressing for 5 to 10 minutes on each breast, repeated two to three times per day. The collected colostrum can be safely combined in the same syringe over a 24-hour period, labeled with the date and time, and then stored in the freezer.
When Pumping Before Delivery is Not Recommended
Specific, high-risk pregnancy conditions serve as absolute contraindications for antenatal expression, regardless of 37 weeks gestation. Any practice that stimulates the release of oxytocin must be strictly avoided to prevent inducing premature labor or causing other complications.
Contraindications for Antenatal Expression
- A history of threatened or actual preterm labor in current or previous pregnancies.
- A diagnosis of placenta previa, which makes expression unsafe due to the risk of hemorrhage.
- Carrying multiple fetuses (e.g., twins or triplets), due to the increased risk of early delivery.
- A short cervix, cervical incompetence, or having a cervical suture (cerclage) in place.
These conditions make the potential risk of stimulating contractions unacceptable, and a healthcare provider will advise against colostrum harvesting entirely.