Fig. 2

Distribution of a AFR (years) and b IBI (months) by income group. Vertical dashed lines indicate modal values for color-matched income groups. a Middle-income countries and WIC participants in the US have the same modal AFR value (20 years), represented by the black, dashed line. b WIC participants and nonparticipants in the US have the same modal IBI value (21 months), represented by the black, dashed line. The upper IBI range has been limited to 120 months. Abbreviations for modal lines: NF, natural fertility; LI, low-income; MI, middle-income; HI, high-income; US WIC, US WIC participant; US NP, US WIC nonparticipant