You mean low waist/hip (or high hip/waist), ie waist less than hip.
And yes it is true:
Women with high WHR (0.80 or higher) have significantly lower pregnancy rates than women with lower WHRs (0.700.79), independent of their BMIs [48]. Therefore, it appears that the lower pregnancy rate in women with high WHR, compared to women with low WHR, is due to a problem with embryo development and its viability. Currently, there is no information available about the incidence or frequency of spontaneous abortion and WHR.
Are those results normalized for sexual activity?
I can see a higher pregnancy rate in low WHRs due to higher propensity for sexual activity instead of the low WHR being an actual indicator of fertility.