Some medications taken by the breastfeeding women are excreted into milk, posing a potential risk of toxicity to the infant. The first line of evidence required for toxicity risk assessment is prediction of drug levels in milk. However, pharmacokinetic (PK) information of drug excretion into milk is largely lacking, or limited to data from case reports. This makes it difficult to provide population-level prediction of drug levels in milk. The lack of data on this topic jeopardizes not only maternal adherence to drug therapy during breastfeeding but also establishment of breastfeeding, even if the drug is considered safe during nursing. Clearly, this clinical problem in drug safety is an important women's health issue, affecting both mother and infant. "Drugs in Lactation" Analysis Consortium (DLAC) is a "drug-in-milk" monitoring network, which is designed as a platform for efficient collection of patient milk samples in a real world setting to generate population predictions of drug excretion levels into human milk.