PIP: Nigeria is described as having the largest population in sub-Saharan Africa in 1991 and as being the tenth largest country in the world. Continued population growth will make Nigeria the fourth most populated country in 2030 after China, India, and the US. The crude birth rate of 46/1000 population and the crude death rate of 15/1000 makes Nigeria one of 12 out of 40 countries in sub-Saharan Africa with a high growth rate. Growth rates are higher in urban than semi-urban and rural areas. Nigeria's prosperous oil boom occurred during 1967-87, when health services expanded and mortality declined. Political instability after 1987 and economic difficulties have resulted in declines in health care delivery. Many deaths among women and children are attributed to malnutrition. The country is expected to have 39.3% of the population living in urban areas by 1995 and 62% by 2025. 20% of Nigeria's urban growth is attributed to growth in Legist alone. The use of family labor for farming contributes to maintaining large family size. The extended family is the dominant economic and security unit for its members, which assures high fertility rates and justifies the belief that high fertility is rewarding. High fertility is maintained through norms perpetuating large family size, early marriage and childbearing, and low contraceptive use. Contraceptive use has increased to 43% of married women and 75% of single women, based on the 1990 Ekiti district study. Use is highest in the southeast and southwest, where marriage age is later than the north. Efforts are being directed to northern regions in order to decrease infant and child mortality and increase contraceptive use. The evidence is interpreted as suggesting that sustained fertility decline is occurring in the southeast and southwest, which together have about 45 million population. The fertility changes are occurring in the context of increased levels of education and other social and economic changes. Sustained fertility decline is considered to be dependent upon the commitment of government, which established a population policy in 1988, to family planning programs and the deterioration of institutions supporting high fertility.