Corticosteroids are first-line drugs for treating a variety of conditions in women of childbearing age, but information concerning how these drugs affect pregnancy is limited. This paper conducts a study and a meta-analysis to determine the risk of major malformations, and more specifically oral clefts, of corticosteroid use on the foetus.

Message

The risk of oral clefts increases threefold in foetuses exposed to corticosteroids during the first trimester.

Reference

L Park-Wyllie et al. Birth defects after maternal exposure to corticosteroids: prospective cohort study and meta-analysis of epidemiological studies. Teratology 2000 62: 385-392.

Study

Participants were women who had voluntarily contacted a counsellor, from the Canadian Motherisk Program, during pregnancy. One group of 184 women had been exposed to prednisone (a synthetic corticosteroid) during pregnancy. The unexposed group of 188 women had enquired about either topical retinoic acid for uncomplicated acne or oral astemizole for seasonal allergies (neither of which has been associated with an increased risk of major malformations).

Information was collected on the mothers' medication, obstetric, medical and genetic history and drug exposure. One year after the expected date of delivery details were collected on the outcome of the pregnancy, birth weight, presence/absence of birth defects and perinatal and neonatal complications (which were corroborated by the child's physician).

In the exposed women, prednisone was administered for an average of 21 weeks (SD 16); the average daily dose was 27 mg (SD 29); and 75% were exposed to it in the first trimester of pregnancy.

The number of major birth defects after corticosteroid use was recorded. Major defects were defined as life-threatening, requiring surgical intervention or having serious cosmetic ramifications. Cases were excluded if factors other than the corticosteroids could have caused the malformation (i.e. genetic syndromes or maternal infections).

Study Results

Compared with the unexposed women, women exposed to corticosteroids were more likely to be smokers. Alcohol consumption and age (average 30 years) did not differ between the two groups.

The number of live-born babies was similar in the exposed and unexposed groups (157 and 171 respectively). There were no differences in the number of miscarriages between the two groups (13 in each), foetal deaths (one in each) or stillbirths (one in unexposed group). The number of elective terminations was higher in the exposed group (16 versus two). Babies born to exposed mothers were smaller (mean 3,112 g versus 3,428 g) were born earlier (mean 38 weeks versus 39.5 weeks) and more likely to be premature (27 babies versus nine). Despite these differences, the majority of babies in both groups were an appropriate weight for their gestational age.