Source: The East African
It's a fact most of us are familiar with through intuition or anecdotes — the longer a girl stays in school, the longer she is likely to delay marriage, and the fewer children she is likely to have.

But East Africa's demographic and health surveys give empirical evidence and lend credence to this belief — that education is the number one factor that will influence when a woman gets married and when she starts having children.

Early marriage and childbirth have been linked to higher maternal mortality, as young mothers are more likely to die during childbirth; and with higher fertility rates, as women who start having children young tend to have many children. [Read: You want an early death? Try giving birth in Kenya]

But expanded opportunities for girls' education have changed the face of East African societies: Women are making decisions on their sexual health, childbearing and marriage that are radically different from their mothers' generations, and shifting the power balance in many societies.

"The drivers that push women towards, or away from marriage and childbearing have changed," says Nairobi-based psychiatrist Frank Njenga. "The world over, education is being used as an effective family planning method."

The latest Kenya and Demographic Housing Survey shows that the median age of marriage increases with advances in education — girls who have no education will get married at about 17.5 years, but those with at least a secondary education will tie the knot at 22.4 years, almost a five year delay. Similarly, in Tanzania, girls who have never been to school will be married by 17.7 years of age, but those who have a secondary education or higher are likely to postpone marriage till 23.1 years.

Octavian Gakuru, an associate professor of sociology at the University of Nairobi attributes this postponement to the values one acquires as a result of schooling. "The school environment and experience open up a person's world view, and makes it more likely that one will delay gratification for the sake of a better future," says Prof Gakuru. "This includes forgoing the initiation of sexual relationships, and by extension, marriage." [Read: Delivering a better future for women and girls]

The effect of education on delaying marriage is less pronounced in Uganda, however. The median age of marriage for Ugandan girls who have never been to school is 17.1 years, according to the latest Demographic and Health Survey. But for girls who complete secondary school, marriage age rises to 21 years, a four-year difference. Overall, Ugandan women tend to get married younger than their East African counterparts — and this is true regardless of the level of educational achievement, urbanisation or wealth.

In Tanzania, the proportion of women who marry by age 15 has been declining over the years; it is 13 per cent among women aged 45-49 compared with only 3 per cent among women aged 15-19.

The median age at first marriage also increases with a rise in household income. Women in the lowest wealth quintile in Kenya are likely to be married by 18.6 years, as marriage offers a quick escape from poverty, if a woman lands a richer man. But women in the highest wealth quintile are likely to postpone marriage until at least 22.6 years, four years later than those from the poorest households.

Fertility is also very closely associated with wealth across the region. The disparity in fertility between the poorest, who have the most children, and the richest women, who have the fewest, is up to four children.

Dr Njenga says: "People in the lower socio-economic status see children as an investment into their own future — the children could lift the parents from poverty in their old age, so they tend to have larger families. But middle class families view children as an expense — more school fees to pay, holidays to cater for and so on."

Again, in Uganda, the difference in median age of marriage across the different income brackets is less pronounced. In the lowest wealth quintile, women are likely to be married by 17.4 years, but in the richest households, the median age of marriage rises by only about two years, to 19.

On the other hand, the marriage age of men does not vary as much as it does for women—whether it is on account of education level, wealth or area of residence.

Men, on average, marry five to six years later than women but there is little difference in the median age at first marriage between men in rural and urban areas. The provincial difference between the highest (Nairobi) and lowest (Nyanza) age at marriage is only three years. People who are relatively poor or who have little education enter into marriage earlier than others, but the difference is more pronounced for women than it is for men.

"The pressures on men and women are completely different, and it's because of how we socialise boys and girls. Men, regardless of social status, don't have the kind of pressure that women are under to get married, so that's why we are seeing less of a disparity. And obviously, there's the issue of the biological clock," says Dr Njenga.

Several studies have shown that education of women is also negatively associated with fertility. Rwanda's interim Demographic and Health Survey, for example, shows that 5.1 per cent of girls aged 15-19 who have never been to school already have a child. But for those in secondary school or higher, only 2.5 per cent in the same age group have had a child.

In Tanzania, young women with no education are more than eight times as likely to have started childbearing by age 19 than those who have secondary or more (52 per cent versus 6 per cent).

In Kenya, women who have never been to school have an average of 6.7 children; this drops dramatically to 3.1 for women with at least some secondary education.

High child mortality contributes to large family sizes among poorer households. With a high chance of death in infancy and childhood, poorer households tend to compensate by having more children. Poorer households are also likely to have more children because children are viewed as a source of easy labour — they can work and contribute to the family's earnings.