small increases in the rates of premarital childbearing, the rates in other regions appear very low.

- Although there is plentiful evidence that early childbearing is correlated with various negative outcomes, rigorous research confirming a causal role for age at birth in producing these outcomes does not exist.  Major global changes such as increasing school enrollment during late adolescence, rising rates of labor force participation among young women, and rising HIV/AIDS prevalence among young women in Africa are likely to have important implications for the transition to parenthood, but little is yet known about the implications of these trends for first parenthood.

# **3. Conceptual Framework**

Our conceptual framework considers the life cycle to have a series of stages. One of those stages is early adolescence, during which for the society that we consider, most individuals complete their formal schooling. For our sample, for example, two-thirds completed their formal schooling by age 13 and over four-fifths by age 15. At the end of the early adolescence stage, we posit that individuals have a vector of human capital stocks (Ka) that include schooling and health. They also are from a parental family that has a vector of characteristics (Fa) such as parental schooling attainment and parental SES. During the next life-cycle stage individuals form unions and initiate parenting, as well as undertake other transitions.<sup>2</sup> These unions are both between individuals and between families, so both individual and family characteristics may affect the timing and the nature of these unions. Let Y be a vector of outcomes that relate to forming their first union and their first parenting – e.g., age of first union, whether first union was a marriage,<sup>3</sup> age of first parenting, age gap between first union and first parenting, whether young first union (under 18 y of age), whether young first parenting (under 18 y of age), partner characteristics (age gap, schooling attainment, health) and partner’s parental family characteristics (parental schooling attainment, land holdings). The basic interest of this study is to estimate how Y depends on schooling, which is one of the components of Ka. We posit that there is a linear approximation to what determines Y given the human capital stocks (Ka) and parental family characteristics (Fa) at the end of early adolescence, unobserved inherent endowments (E0) such as innate ability and charm and a vector of stochastic disturbance terms, one each for each different outcome (U): (1) Y = a0 + a1 Ka + a2 Fa + a3 E0 + U, where the ai are matrices of coefficients to be estimated and where all the coefficients may differ by gender. .

The questions that are posed in the introduction pertain to obtaining good (consistent) estimates of the coefficients of schooling in relation (1), which is one of the components of Ka, for each of the components in Y. But estimation of relation (1) is a challenge because the human capital stocks at the end of the early-adolescent stage (Ka) all reflect previous behavioral choices so OLS, simple probit or similar estimates of relation (1) are likely be inconsistent due to endogeneity. We assume

> 2 Only 4% of our sample initiated their first union prior to completing formal schooling.  That is not a large enough subsample to permit treating them differently in the analysis, so we combine this 4% with the other 96% in the analysis even though they formed unions prior to completing formal schooling.

> 3 At the time of the 2002-4 survey (see Section 4.1 below), the majority of those in unions were formally married, but a substantial minority (44%) of those who were in unions were not married.

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