The primary driver of lactation past 10 days postpartum is milk removal. If the breasts aren’t emptied (i.e., the stored milk is removed to the point that the breasts feel soft and/or hand-expressing more is difficult) at feedings, the body makes less milk to compensate. Optimizing breastfeeding techniques is therefore important for sustained and bountiful milk production (see below).
Stress/anxiety, medications (e.g., oral birth control), menstruation, fatigue, hormonal conditions, genetics, and breast surgery can also affect lactation.[1] Many prescription and over-the-counter medications and recreational drugs, including alcohol, can be expressed in human milk, but not all of them are expressed at levels that could be harmful to the breastfeeding infant.[2][3]
If planning or needing to take medications or recreational drugs while breastfeeding, it’s wise to check with a knowledgeable healthcare provider, such as a doctor or pharmacist.