The article offers information on the use of sildenafil citrate (SC) in obstetrics. Topics discussed include role of phosphodiesterases (PDE) in regulating cell function, which contain 11 isoenzymes from which PDE-5 is inhibited by SC; role of SC in combination with nifedipine in preventing threatened preterm labor; and benefits of SC among women with pre-eclampsia and fetal growth restriction fetuses.