Effective medical treatment of rheumatic diseases during pregnancy and lactation is important, but the evidence for use of biological disease-modifying anti-rheumatic drugs (bDMARDs) is sparse and recommendations conflicting, which we discuss in this review. While some tumour necrosis factor (TNF)-α inhibitors appear safe during pregnancy and lactation, the evidence for use of non-TNF-α inhibitors is still too sparse to exclude adverse pregnancy outcomes and harm to the lactating child. The limited evidence on paternal exposure indicates, that TNF-α inhibitors do not affect male fertility or harm offspring. For non-TNF-α inhibitors, the evidence is still insufficient to draw any conclusion.