Pharmacological agents in pregnancy to improve fetal conditions: prevention of fetal cardiac insufficiency, consequences of congenital adrenal hyperplasia and respiratory distress syndrome.
Improved prenatal diagnostics of fetal diseases have made it necessary to evaluate and develop maternal pharmacological treatment programs to improve fetal condition. In fetal cardiac insufficiency due to persistent tachyarrhythmias, maternal treatment, e.g., with either digoxin alone or combined with other drugs, makes it possible to continue pregnancy in preterm patients with risk of fetal cardiac failure and decreases mortality and morbidity. The loading dose of digoxin can be given either intravenously to the mother or when fetal hydrops is already present directly into the fetal buttock. Maternal oral treatment is initiated simultaneously and continued until delivery is possible. If no response is achieved in 3 days, other regimens are used. Severe virilization of female fetuses due to congenital adrenal hyperplasia and 21-hydroxylase deficiency can be prevented by starting oral maternal dexamethasone (1.0-1.5 mg/day) treatment no later than at the 7th week of pregnancy. Later analysis of chorion villous cells at the 10-11th week of pregnancy reveals whether the fetus is affected or healthy. If affected, the treatment has to be continued until delivery. Maternal corticosteroid therapy to prevent respiratory distress syndrome (RDS) of preterm infants must be given at least 24-48 hours before delivery to get any benefit. The two regimens used are betamethasone 12 mg twice with an interval of 24 hours, and dexamethasone 12 mg twice with an interval of 12 hours. Serial treatments with an interval of 7-14 days further decrease the risk of RDS, but simultaneously the possibility of side effects such as fetal growth retardation and postnatal endocrinological disorders increases.
Halmesmaki
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Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Helsinki, Finland.