Much lower levels of fertility in urban than rural areas throughout sub-Saharan Africa imply that fertility decline in the region may be facilitated by rapid urbanization and rural-to-urban migration. The present study uses data from Demographic and Health Surveys in six countries--Ghana, Kenya, Mali, Senegal, Togo and Uganda--to assess the impact of long-term rural-urban female migration on fertility. Results of logit analyses indicate that in most countries women who leave the countryside represent the higher fertility segment of the rural population in the years before migration. Migrants' risk of conception declines dramatically in all countries around the time of migration and remains lower in the long run among most migrant groups than among rural and urban nonmigrants. Descriptive analyses suggest that the decline in migrant fertility is related to the rapid and pronounced improvement in standard of living experienced by migrants after settling in the urban area and may be due in part to temporary spousal separation.