Many women use medication during pregnancy. Both the healthcare professional and the pregnant woman often have many questions about the possible adverse effects of the medication that are not always answered in the product information. The Teratology Information Service (TIS), a part of the Netherlands Pharmacovigilance Centre Lareb, is a centre of expertise in the field of the safety of medication use and other external influences during spermatogenesis, pregnancy and lactation. The TIS collects, interprets, and disseminates information that can contribute to patient care. Healthcare professionals can contact the TIS for information and individual risk assessments. In this article we discuss the background and positioning of the TIS, the characteristics of telephone consultations, the collection of data and the considerations that are important for the use of medication during pregnancy and lactation.