"The conclusion that Roe had a relatively modest impact on birth rates is somewhat at odds with previous work (Gruber, Levine and Staiger 1999; Levine et al. 1999; Levine 2004). These authors argued that national legalization in 1973 led to an equally large decrease in birth rates in the non-repeal states as had occurred in the repeal states in the previous three years. Gruber, Levine and Staiger (1999) refer to this as the “bounce back” effect of Roe. However, they lack a comparison group after 1973. Consequently, they cannot distinguish the “bounce back” effect from a relatively larger decrease in birth rates in the repeal states relative to the non-repeal states in the pre-Roe years followed by no meaningful effect of Roe in the subsequent years.19 Although the latter seems surprising given the dramatic change in distance to the nearest abortion provider between 1972 and 1973 (Figure 7), trends in birth rates are consistent with this interpretation."