Psoriasis Treatments during Pregnancy — What is Safe?
Psoriasis treatments require special precautions before, during, and after pregnancy. This is an important topic to discuss with patients of childbearing age who are pregnant or considering pregnancy.
Fetal risks in pregnant women with psoriasis derive both from maternal disease and the medications used to control the illness. 
Topical agents are typically considered a safer route than other medications. They are thought to be less likely to harm the fetus, because they have little systemic absorption. However, a study has come out recently looking at the safety profile of topical agents in relation to the baby.
This study from the Journal of Drugs in Dermatology, July 2016, reviews the recommendation on using topical dermatological medication in pregnancy. The results of this study show that none of the topical medications are safe for treatment in the first trimester and some are totally contraindicated for use in pregnancy. 
See the chart below to refer for the ratings:
A simple and effective alternative to psoriasis medications during pregnancy is Narrowband UVB light from phototherapy. Narrowband UVB light has long been considered to be a second line treatment, as it has not been associated with an increase in risk of fetal abnormalities or prematurity. In cases with extensive lesions, this seems to be the safest therapy, as long as overheating during treatment is avoided, especially during the first 28 days of gestation, due to the increased risk of neural tube defects.
With these new recommendations on topical dermatologic medications Narrowband UVB phototherapy should be considered the first line treatment for women of childbearing age with psoriasis.
 Patricia SK, Clarissa CF, Lucas SCN, Licia MHM. “Treatment of psoriasis and psoriatic arthritis during pregnancy and breastfeeding” An Bras Dermatol. 2015 May-Jun; 90(3): 367–375. doi: 10.1590/abd1806-4841.20153113
 Viral MP, Robert AS, W. Clark L. “Safety of Topical Dermatologic Medications in Pregnancy”. Journal of Drugs in Dermatology. July 2016 | Volume 15 | Issue 7.