Thanks to Brendan P. Foht, over at The Corner, for showing that it was misleading to claim that SCNT human cloning could not lead to a human pregnancy because there have been no successful cloned monkey pregnancies. But there have been cloned monkey pregnancies, with one embryo developing to the fetal stage with a heartbeat! From the 2010 article in the International Journal of Biological Development:
At present, the production of live primate offspring following SCNT has yet to be accomplished (Mitalipov et al., 2002; Simerly et al., 2003). We summarize here our recent unpublished efforts in embryo transfer using rhesus blastocysts produced by SCNT with adult monkey skin cells expressing GFP (Table 3). A total of 5 pregnancies were established following transfer of 67 embryos into 10 recipients (Tables 3 and 4). Only one pregnancy resulted in a live fetus that possessed a fetal heartbeat, detected by ultrasonographic scans, while other pregnancies contained sacs without a fetus (Fig. 2). Unfortunately, this pregnancy failed to go to term and was aborted at day 81 of gestation.
The same early difficulties were experienced by researchers in cloning other mammals. But starting with Dolly, difficulties bringing a cloned fetus to birth were eventually overcome.
Bottom line: Monkeys have been impregnated successfully with cloned embryos, resulting in some gestational success. The rest is simply a matter of technique. Eventually, a cloned monkey infant will almost certainly be born. The very research now being conducted in human cloning is a required step toward attaining that same potential end with us.