Treatment with light therapy
Both components in PUVA treatment—the oral medication psoralen and the UVA light—should be avoided by both sexes around conception and by women during pregnancy as they can cause birth defects. This also applies to bath PUVA, where the entire body is immersed in a tub of water that contains psoralen.
Nursing women should avoid PUVA, because psoralen in breast milk could cause light sensitivity in the infant.
Ultraviolet light B (UVB)
Treatment with UVB is generally safe during pregnancy, but sunscreens should be applied on the face to prevent melasma (a condition common in pregnant women that causes the appearance of brown spots). UVB is generally acceptable as a psoriasis treatment for women who are nursing.
Combination treatments of UVB with tar or anthralin (called Goeckerman or Ingram regimens, respectively) are considered safe and effective treatment options for pregnant women with widespread psoriasis. These treatments have been used for decades without any evidence of harm to the fetus.