I construct and partially characterise the solution of a life-cycle model of fertility choice and human capital accumulation. Because it takes time to raise children, women face a trade-off between lifetime earnings and childbearing. The model implies that (i) earnings must drop discontinuously at the time of a birth; (ii) age at first birth and human capital will be positively correlated; and (iii) a permanently higher demand for skill causes women to delay first births. I show that the second of these predictions holds in a sample of South African women drawn from the first wave of the National Income Dynamics Study.