Demeclocycline has been assigned to pregnancy category D by the FDA. Animal studies have revealed evidence of embryotoxicity and teratogenicity associated with the use of tetracyclines. Demeclocycline crosses the placenta with cord concentrations averaging 65% of maternal blood levels. There are no controlled data in human pregnancies; however, congenital defects associated with the use of tetracyclines has been reported, including toxic effects on skeletal formation. When used during tooth development (second half of pregnancy) tetracyclines may cause permanent yellow-gray-brown discoloration of the teeth and enamel hypoplasia. Demeclocycline should only be given with extreme caution, if at all, during pregnancy. Demeclocycline is only recommended for use during pregnancy when there are no alternatives and benefit outweighs risk. Pregnant patients or patients who become pregnant during demeclocycline therapy should be advised of the potential hazards to the fetus.

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There are no data on the excretion of demeclocycline into human milk; however, tetracyclines are excreted into human milk in small amounts. Concentrations of tetracycline in milk have averaged 0.6 mcg/mL when the blood level was approximately 1.2 mcg/mL. The theoretical risks of dental staining and inhibition of bone growth exist, although they are unlikely. In one study, tetracycline levels were undetectable in nursing infants. Tetracycline, a related drug, is considered compatible with breast-feeding by the American Academy of Pediatrics. The manufacturer recommends that due to the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

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