to occur.35 In rats and rabbit studies, topical tazarotene caused reduced fetal body weights, reduced skeletal ossification, and retinoid malformations including spina bifida, hydrocephaly, and cardiovascular anomalies. Of 9 reported human pregnancies that were inadvertently exposed to topical tazarotene, 1 patient decided to terminate her pregnancy for non-medical reasons unrelated to tazarotene, while the other 8 pregnancies delivered apparently healthy babies.36 Because tazarotene is a retinoid and some animal studies reported adverse effects, it is classified as pregnancy category X and should be avoided during pregnancy. And before prescribing to young women of child bearing age, a pregnancy test should be ordered 2 weeks before starting medication.
Tretinoin, Category C
There is limited human data on topical tretinoin safety in pregnancy. Five early case reports indicated ear, cardiovascular, and neurological malformations. However, two subsequent larger trials involving a total of 300 pregnancies indicated no teratogenic potential.37-40 Another prospective study of 106 women treated topically with tretinoin in first-trimester did not report higher malformation or spontaneous abortion rate.41 Topical tretinoin studies in animals have revealed bone anomalies (short, bent,
or incompletely ossified bones), skull anomalies, hydrocephalus, and increased intrauterine death.42 Although some studies cited above recommend its use in pregnancy, especially after first-trimester, most experts avoid its use during pregnancy.25
Isotretinoin, Category X
Topical isotretinoin is absolutely contraindicated in pregnancy due to ample data showing increased pregnancy loss in first-trimester and numerous birth defects, some of which are hydrocephalus, cleft palate, ear canal stenosis, thymic defects, spina bifida, and cardiac conotruncal malformations.7,43 In the United States, isotretinoin users must register with iPLEDGE, which is a national registry that is designed to prevent fetal exposure to isotretinoin. Periodic pregnancy tests are required before drug refills are issued by pharmacy. However, some studies are skeptical if such programs actually decrease fetal exposure to isotretinoin, which makes it imperative for physicians to counsel their patients on the dangers of becoming pregnant while using isotretinoin.44,45
Adapalene, Category C
In animal studies, topical adapalene has not been shown to be fetotoxic, with only minimal increase in occurrence of
