An estimated 6% of pregnant women receive prescription topical corticosteroids (TCS), which are pregnancy risk category C. Animal studies show teratogenic effects, but data are limited and conflicting regarding use in pregnant women.
Investigators performed a retrospective cohort study using data from the U.K. National Health Service. They documented type and dosages of TCS prescriptions filled at pharmacies by 2658 pregnant women over a 7-year period, who were matched with 7246 unexposed pregnant controls. Mean dispensed quantity of potent or very potent topical steroids during the whole pregnancy was 64 grams (range, 15–490). Women who received corticosteroids via other routes during pregnancy and those with multiple pregnancy or assisted reproduction were excluded. A subgroup who received TCS during the first trimester was identified (the critical period for fusion of the lip/palate is the 5th–12th gestational week). Other outcomes studied included low birth weight (LBW, <2500 g), preterm delivery (<37 weeks’ gestation), fetal death, mode of delivery (vaginal vs. C-section), and low Apgar score (<7 at 5 minutes). Confounding concurrent diseases were noted.
Compared with no TCS use, maternal TCS exposure was NOT associated with orofacial cleft, LBW, preterm delivery, fetal death, low Apgar score, or mode of delivery. A separate analysis showed a significantly increased risk for LBW when the dispensed amount of potent or very potent TCS exceeded 300 g during the entire pregnancy.
Risks to the foetus from topical corticosteroid exposure appear to be lower than feared, but a dose-dependent relationship with low birth weight was seen. Many patients do not use up their prescriptions, and unaccounted-for TCS may have been received elsewhere, so the risks for adverse outcomes may be underestimated by this study design. Because LBW seems to correlate with quantity of potent TCS exposure, limited amounts of mild or moderate-strength TCS are safest in pregnant women. When potent or very potent TCS are indicated, the cumulative amount should be kept under 300 g, and fetal growth should be monitored.
by Mary Wu Chang, MD reviewing Chi C-C et al. JAMA Dermatol 2013 Sep 4.