Universidad de los Andes, Santiago, Chile
Email: pmgdr{at}manquehue.net
Sir,
The paper by Ortiz et al. (2004), which concludes that Post-coital administration of levonorgestrel does not interfere with post-fertilization events in the new-world monkey Cebus apella, has no scientific basis. The conclusions are not supported by the results reported, namely, in order to demonstrate that after levonorgestrel administration there is a living embryo it is necessary to find cardiac activity in the gestational sac. The authors did not mention cardiac activity in the ultrasound examinations of gestational sacs. Were they living embryos or dead embryos? Dead embryos not yet delivered are missed abortions as all obstetricians know.
In the human species 1015% of clinical pregnancies are aborted spontaneously. Cebus apella monkeys also have spontaneous abortions. In this paper the authors did not mention any spontaneous abortion in cases or controls. Obviously, the number of cases is inadequate for a scientific demonstration of the hypothesis: only 24 treatment cycles and 24 control cycles.
In my opinion this important research should be repeated with two conditions: (i) ultrasonographic examination of cardiac activity in all gestational sacs with a longer period of observation (pregnancies were aborted too early, on day 15 or 16 of the luteal phase, without a chance to observe appearance of cardiac activity); (ii) detection of spontaneous abortion rate in Cebus apella followed by a calculation of the necessary number of treatment and control cycles in order to be able to confirm or reject the hypothesis.
References
Ortiz ME, Ortiz RE, Fuentes MA, Parraguez VH and Croxatto HB (2004) Post-coital administration of levonorgestrel and post-fertilization events in the new-world monkey Cebus apella. Hum Reprod 19, 13521356.
Submitted on July 5, 2004; accepted on December 10, 2004.