Human Reproduction, Vol. 16, No. 1, 198-199,
January 2001
© 2001 European Society of Human Reproduction and Embryology
Letters to the Editor |
1 Fukuda Ladies Clinic, 30–9 Kariya, Ako, Hyogo 678-0239, Japan 2 Laboratory of Reproductive Biology, University Hospital of Copenhagen Section 5712, Blegdamsvej 9, DK-2100, Copenhagen, Denmark
Dear Sir,
We thank Dr William H. James for his interest in our work. Based on observations in the Mongolian gerbil, on which more males are conceived when oocytes derive from the right ovary compared with oocytes from the left ovary, he suggests that a similar skewness of gender also may apply to oocytes from women.
Although we do not have a complete set of information with regard to the gender of children born, who were included in our published study (Fukuda et al., 2000
), we do have information from ~50% of all the pregnancies, partly due to spontaneous and artificial abortions. In the group of infertile women, the side in which the dominant follicle developed was monitored, whereas corpus luteum was determined during early pregnancy of ~5–9 weeks in the group of fertile women. The sex of the fetus was determined at ~5 months gestation according to the ultrasound method by Natsuyama (1984). Table I shows the available data with regard to whether the oocyte originated in the right or left ovary correlated to gender of the resulting child. In infertile women the frequency of boys resulting from oocytes originating in the right ovary is 0.685, which seems to be higher than in oocytes originating in the left ovary (0.462). This difference is close to statistical significance (P = 0.0545). In the group of fertile women the ratio of boys from right-sided ovulations was 0.528 compared to 0.515 from oocytes originating in the left ovary; a difference which did not reach statistical significance. Although our data did not reach statistical significance, they did show a trend towards more boys resulting from oocytes originating in the right ovary compared with oocytes from the left ovary. We obviously need more information and to continue to accumulate data.
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The issue of whether the more frequent incidence of ovarian cancer in the right than in the left ovary could be related to a different endocrine profile of the two ovaries is also interesting. We are, however, a bit reluctant to take this suggestion as Dr William H.James does. There may exist anatomical differences between the right and left side with regard to the reproductive organs; this may account for the difference between the observed endocrinological parameters, but whether this also relates to the risk of achieving ovarian cancer is uncertain. In addition, we are aware of other studies which were unable to confirm the older studies of Mueller et al. 1950 (Balasch et al., 1994
; Hartge and Devesa, 1995). However, the proposition is interesting and deserves a more detailed study.
Notes
3 To whom correspondence should be addressed.E-mail: fukuda8767{at}gem.bekkoame.ne.jp 
References
Balasch, J., Penarrubia, J., Marquez, M. et al. (1994) Ovulation and ovarian cancer. Gynecol. Endocrinology, 8, 51–54[Web of Science][Medline]
Fukuda, M., Fukuda, K., Yding Andersen, C. and Byskov, A. G. (2000) Right-sided ovulation favours pregnancy more than left-sided ovulation. Hum. Reprod., 15, 1921–1926
Hartge, P. and Devesa, S. (1995) Ovarian cancer, ovulation and side or origin. Br. J. Cancer, 71, 642–643[Medline]
Mueller, C. W., Topkins, P. and Lapp, W.A. (1950) Dysgerminoma of the ovary. Am. J.Obstet. Gynecol., 60, 153–159
Natsuyama, E. (1984) Sonographic determination of fetal sex from twelve weeks of gestation. Am. J. Obstet. Gynecol., 149, 748–757[Medline]
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