OUTCOME AFTER MATERNAL VARICELLA INFECTION IN THE FIRST 20 WEEKS OF PREGNANCY

Background. Infection with the varicellazoster virus during pregnancy can produce an embryopathy characterized by limb hypoplasia, eye and b rain damage, and skin lesions. The risk is greatest when infection occ urs during the first 20 weeks of pregnancy, but the magnitude of the r isk is uncertain. Methods. We studied 106 women with clinically diagno sed varicella infection in the first 20 weeks of pregnancy and compare d the outcomes with those in 106 age-matched, nonexposed controls. Res ults. Among the women with varicella, there was a trend toward more el ective terminations of pregnancy (14 percent, vs. 7.5 percent among th e controls; P = 0.1), corresponding to a significantly higher percepti on of teratogenic risk (P = 0.03). The proportions of miscarriages and live births and the mean birth weights were similar in the two study groups; there were more premature births (less than or equal to 37 wee ks) among the women with varicella infection (14.3 percent vs. 5.6 per cent, P = 0.05). Congenital defects occurred in four infants born to t he women with varicella (varicella embryopathy, hydrocephalus, meningo cele and clubfeet, and hammer toe) and two infants born to the control s (ventricular septal defect and hip dislocation). The risk of varicel la embryopathy after infection in the first 20 weeks was 1.2 percent ( 95 percent confidence interval, 0 to 2.4 percent). When we pooled our results with those from other prospective studies, the mean risk of em bryopathy after infection with varicella-zoster virus in the first tri mester was 2.2 percent (95 percent confidence interval, 0 to 4.6 perce nt). Conclusions. The absolute risk of embryopathy after maternal vari cella infection in the first 20 weeks of pregnancy is about 2 percent.