ORAL POLIO VACCINATION DURING PREGNANCY - LACK OF IMPACT ON FETAL DEVELOPMENT AND PERINATAL OUTCOME

Prompted by a nascent epidemic of poliomyelitis in Finland, a mass vac cination program with live oral poliovirus vaccine (OPV) was implement ed in February and March 1985. The final rate of coverage was similar to 94%. Pregnant women were included, and a cohort study was launched to evaluate any harmful effects of OPV on the developing embryo. All r ecords of births to mothers who were pregnant during the period of vac cination and whose infants were delivered at the three major hospitals in the Helsinki area were reviewed. Within the study cohort, mothers were grouped into three categories according to their trimester of pre gnancy during the program. In addition, two reference cohorts were eva luated; these cohorts consisted of infants delivered at the same hospi tals during the second half of 1984 and of 1986, respectively. Each of the three categories in the study cohort included similar to 3,000 ch ildren, while each reference cohort included similar to 6,000 children . Data were analyzed on the rate of intrauterine growth and the preval ences of stillbirth, neonatal death, congenital malformation, prematur e birth, perinatal infection, and neurological aberration. No differen ces were documented among the study and reference cohorts or among the three categories within the study cohort. Thus, under the conditions described here, the inclusion of pregnant women in programs of mass va ccination with OPV appears to be safe.