During the last decades, there has been a trend for increased consumption of prescribed or over-the-counter medications by pregnant women. Although the use of psychotropic medications during pregnancy and lactation is likely, limited evidence regarding their safe use exists. In this chapter, we summarize the current available evidence on the pharmacokinetics of anxiolytics, antidepressants, antipsychotics, mood stabilizers, and opioids in the pregnant woman, the fetus, and the lactating infant. Dynamic changes in the female physiology during pregnancy affect several pharmacokinetic parameters of psychotropics and amplify the already present sex differences in drug absorption, distribution, metabolism, and elimination. Characteristics of psychotropic compounds that minimize the exposure of the fetus are: higher protein binding, smaller distribution volume, shorter half-life, and ideally good affinity with efflux transporters. Regarding breastfeeding, drug levels in the infant of less than 10% of the maternal levels are considered safe and many common psychotropics fall well below that limit. Therefore, breastfeeding could be allowed for several psychotropic medications, based on the available evidence. Importantly, interventions that reduce exposure of the infant should be chosen. Ideally, for drugs frequently used in pregnancy and lactation, more studies should be conducted, in order to assist clinicians and patients to take better-informed decisions.