SEX RATIO OF MALE SEX PRESELECTED CHILDREN BORN TO COUPLES WITH EXCLUSIVELY FEMALE OFFSPRING
Syst Biol Reprod Med Downloaded from informahealthcare.com by McMaster University on 10/28/14 For personal use only.
S. A. ERICSSON and R. J . ERICSSON
The present study was undertaken to determine if couples with exclusively female children had a decreased probability of a male child after using male sex preselection. Selection criteria for subjects necessitated that couples have had only female children previously and had produced a child at one of 14 centers after using protocol 3 (n = 70) and modified 3 (n = 28) male sex preselection. Prior to sex selection, protocol 3 couples produced a combined total of 135 female children for an average of 2.01 (range 1-4) females per couple; modified 3 couples produced a combined total of 62 female children for an average of 2.21 (range 1-4) females per couple. The normal approximation to the binomial distribution was used to determine significant differences between the sex ratios prior to and after male sex preselection. For couples using protocol 3 there were significant differences in the sex ratio prior to sex preselection (0%)and after sex preselection (73.0%) (p < .oooO3).There were also significant differences between the sex ratio prior to modified 3 (0%) and after sex preselection (86%) (p < .oooO3). Couples using male sex preselection do not have a decreased probability of a male child if they have had exclusively female children. Key Words: Sperm, Sex preselection, Fertility, Infertility, Child.
INTRODUCTION It has been suggested by some clinicians that couples using male sex preselection have a decreased probability of a male child if they have had exclusively female children [2]. This is supported somewhat in the general population by reports that the sex of previous children [3] marginally affects the sex ratio. The purpose of this study was to determine if couples with only female offspring and using male sex preselection had a significant change from their previous sex ratio.
MATERIALS AND METHODS Subjects. Couples that produced a child using protocol 3 albumin separation (n = 70) and modified protocol 3 albumin separation (n 20) at 14 Sperm Centers were selected for this study. Selection criteria necessitated that these couples have had only female children prior to treatment. Protocol 3 albumin separation couples produced a total of 135 female children for an average of 2.01 (range 1-4)
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Received October 9, 1991. From Gametrics Limited, Alzada, MT, USA. Address correspondence to Scott A. Ericsson, Gametrics Ltd, HC69,Box 50, Alzada, MT 59311 USA. ARCHIVES OF ANDROLOGY 28:121-123 (1992) Copyright 0 1992 by Hemisphere Publishing Corporation
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Syst Biol Reprod Med Downloaded from informahealthcare.com by McMaster University on 10/28/14 For personal use only.
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PROTOCOL 3
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FIGURE 1 The sex ratio (expressed as a percentage) prior to sex selection and the sex ratio after using protocol 3 or modified 3. per couple; modified 3 albumin separation couples produced a total of 62 female children for an average of 2.21 (range 1-4) per couple. Separation Techniques. Protocol 3 albumin separation process [l] is a method used for male sex preselection which starts with diluting the ejaculate by an equal. volume of Tyrodes's salt solution (Sigma Chemical Co., St. Louis, MO). The diluted sample is then divided into 0.5-mL aliquots, each containing 15 x lo6 washed sperm. These aliquots are then layered over a 7.5% solution of human serum albumin (hSA) (Alpha Therapeutic Corp., Los Angeles, CA) for 1 h in an 8 X 75-mm glass column. A pipette is used to remove the initial serum layer and the albumin is centrifuged at 28003200 rpm for 10 min. The sperm pellet is resuspended in Tyrodes's salt solution prior to layering over a two-layer hSA column, 12.5% at the top and 20% at the bottom. At 1 h the sperm layer is removed and at 1.5 h the 12.5% layer is removed. The 20% hSA layer is then centrifuged for 10 min and the sperm pellet is resuspended in 0.25 mL of Tyrodes's salt solution. Modified protocol 3 albumin separation process for male sex preselection is similar to protocol 3, with the exception of a reduction of isolation time by 45 min and an increase in hSA concentration from 7.5 to 10% for step 1 of the isolation procedure. Step 1 in modified protocol 3 goes from 1 h to 4 5 min. Step 2 goes from 1.5 h to 1 h for a total reduction of 45 min. Statistical Analysis. The minimum sample sizes required to detect significant differences between sex ratios was determined from a formula given by Moore and Gledhill [4]. Significant differences between the percentage of males born to couples prior to and after male sex preselection was assessed using the normal approximation to the binomial distribution [4].
RESULTS There was a significant difference in the sex ratio (expressed as a percentage) prior to sex preselection (0%) and the sex ratio after using protocol 3 (73.0%) (p < .00003) (Fig. 1).
Sex Preselection
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Comparison of the sex ratio prior to sex preselection (0%) and the sex ratio after using modified 3 (86%) showed that they were significantly different 0) < .oooO3)(Fig. 1).
Syst Biol Reprod Med Downloaded from informahealthcare.com by McMaster University on 10/28/14 For personal use only.
DISCUSSION Previous studies have illustrated the influence of the sex of previous children [3] on the sex ratio of the general population. These same factors do not appear to decrease the sex ratio of children born to couples using male sex preselection. This is illustrated by the significant difference between the sex ratio prior to and after male sex preselection for couples using either protocol 3 or modified 3. We conclude that having only female children previously does not decrease the sex ratio of children born to couples using male sex preselection.
REFERENCES 1. Beernink FJ, Ericsson RI (1982): Male sex preselection through sperm isolation. Fertil Steril 38:493-495 2. Bibbins PE Jr, Lipshultz LI, Ward, JB Jr, Legator MS (1988): Fluorescent body distribution in spermatozoa in the male with exclusively female offspring. Fertil Steril 49570-675 3. McClelland GH (1983): Measuring sex preferences and their effects on fertility. In: Sex Selection of Children. NG Bennett (ed).New York: Academic, pp 13-45 4. Moore DH, Gledhill BL (1988): How large should be my study be so that I can detect an altered sex ratio. Fertil Steril 50:21-25
Syst Biol Reprod Med Downloaded from informahealthcare.com by McMaster University on 10/28/14 For personal use only.
S. A. ERICSSON and R. J . ERICSSON
The present study was undertaken to determine if couples with exclusively female children had a decreased probability of a male child after using male sex preselection. Selection criteria for subjects necessitated that couples have had only female children previously and had produced a child at one of 14 centers after using protocol 3 (n = 70) and modified 3 (n = 28) male sex preselection. Prior to sex selection, protocol 3 couples produced a combined total of 135 female children for an average of 2.01 (range 1-4) females per couple; modified 3 couples produced a combined total of 62 female children for an average of 2.21 (range 1-4) females per couple. The normal approximation to the binomial distribution was used to determine significant differences between the sex ratios prior to and after male sex preselection. For couples using protocol 3 there were significant differences in the sex ratio prior to sex preselection (0%)and after sex preselection (73.0%) (p < .oooO3).There were also significant differences between the sex ratio prior to modified 3 (0%) and after sex preselection (86%) (p < .oooO3). Couples using male sex preselection do not have a decreased probability of a male child if they have had exclusively female children. Key Words: Sperm, Sex preselection, Fertility, Infertility, Child.
INTRODUCTION It has been suggested by some clinicians that couples using male sex preselection have a decreased probability of a male child if they have had exclusively female children [2]. This is supported somewhat in the general population by reports that the sex of previous children [3] marginally affects the sex ratio. The purpose of this study was to determine if couples with only female offspring and using male sex preselection had a significant change from their previous sex ratio.
MATERIALS AND METHODS Subjects. Couples that produced a child using protocol 3 albumin separation (n = 70) and modified protocol 3 albumin separation (n 20) at 14 Sperm Centers were selected for this study. Selection criteria necessitated that these couples have had only female children prior to treatment. Protocol 3 albumin separation couples produced a total of 135 female children for an average of 2.01 (range 1-4)
-
Received October 9, 1991. From Gametrics Limited, Alzada, MT, USA. Address correspondence to Scott A. Ericsson, Gametrics Ltd, HC69,Box 50, Alzada, MT 59311 USA. ARCHIVES OF ANDROLOGY 28:121-123 (1992) Copyright 0 1992 by Hemisphere Publishing Corporation
121
S. A. Ericsson and R. J. Ericsson
122
z
w n
9I u
U.
Syst Biol Reprod Med Downloaded from informahealthcare.com by McMaster University on 10/28/14 For personal use only.
0
ti-
a
It
I?&
PRIOR TO SEX PRfSELECllOld
PROTOCOL 3
19
6-
0
msi SEX
Pwon TO SEX
PRESElECllON
PRESELECllOll
21
4
r o s SEX PRESELECI ION
PROTOCOL MODIFIED 3
1 0htALE 0rEMALE
1
FIGURE 1 The sex ratio (expressed as a percentage) prior to sex selection and the sex ratio after using protocol 3 or modified 3. per couple; modified 3 albumin separation couples produced a total of 62 female children for an average of 2.21 (range 1-4) per couple. Separation Techniques. Protocol 3 albumin separation process [l] is a method used for male sex preselection which starts with diluting the ejaculate by an equal. volume of Tyrodes's salt solution (Sigma Chemical Co., St. Louis, MO). The diluted sample is then divided into 0.5-mL aliquots, each containing 15 x lo6 washed sperm. These aliquots are then layered over a 7.5% solution of human serum albumin (hSA) (Alpha Therapeutic Corp., Los Angeles, CA) for 1 h in an 8 X 75-mm glass column. A pipette is used to remove the initial serum layer and the albumin is centrifuged at 28003200 rpm for 10 min. The sperm pellet is resuspended in Tyrodes's salt solution prior to layering over a two-layer hSA column, 12.5% at the top and 20% at the bottom. At 1 h the sperm layer is removed and at 1.5 h the 12.5% layer is removed. The 20% hSA layer is then centrifuged for 10 min and the sperm pellet is resuspended in 0.25 mL of Tyrodes's salt solution. Modified protocol 3 albumin separation process for male sex preselection is similar to protocol 3, with the exception of a reduction of isolation time by 45 min and an increase in hSA concentration from 7.5 to 10% for step 1 of the isolation procedure. Step 1 in modified protocol 3 goes from 1 h to 4 5 min. Step 2 goes from 1.5 h to 1 h for a total reduction of 45 min. Statistical Analysis. The minimum sample sizes required to detect significant differences between sex ratios was determined from a formula given by Moore and Gledhill [4]. Significant differences between the percentage of males born to couples prior to and after male sex preselection was assessed using the normal approximation to the binomial distribution [4].
RESULTS There was a significant difference in the sex ratio (expressed as a percentage) prior to sex preselection (0%) and the sex ratio after using protocol 3 (73.0%) (p < .00003) (Fig. 1).
Sex Preselection
123
Comparison of the sex ratio prior to sex preselection (0%) and the sex ratio after using modified 3 (86%) showed that they were significantly different 0) < .oooO3)(Fig. 1).
Syst Biol Reprod Med Downloaded from informahealthcare.com by McMaster University on 10/28/14 For personal use only.
DISCUSSION Previous studies have illustrated the influence of the sex of previous children [3] on the sex ratio of the general population. These same factors do not appear to decrease the sex ratio of children born to couples using male sex preselection. This is illustrated by the significant difference between the sex ratio prior to and after male sex preselection for couples using either protocol 3 or modified 3. We conclude that having only female children previously does not decrease the sex ratio of children born to couples using male sex preselection.
REFERENCES 1. Beernink FJ, Ericsson RI (1982): Male sex preselection through sperm isolation. Fertil Steril 38:493-495 2. Bibbins PE Jr, Lipshultz LI, Ward, JB Jr, Legator MS (1988): Fluorescent body distribution in spermatozoa in the male with exclusively female offspring. Fertil Steril 49570-675 3. McClelland GH (1983): Measuring sex preferences and their effects on fertility. In: Sex Selection of Children. NG Bennett (ed).New York: Academic, pp 13-45 4. Moore DH, Gledhill BL (1988): How large should be my study be so that I can detect an altered sex ratio. Fertil Steril 50:21-25
