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At least 19 recordsLinked to original sources
PubMedDate not supplied

The effects of sex preselection on the sex ratio of families.

Advances in the potential for couples to predetermine the sex of their children will have significant consequences for many aspects of society. Among the likely demographic impacts are changes in both population size and the sex ratio. The aim of this article is to assess the effects of sex preselection on the sex ratio of families. The expected family sex ratio is derived and characterized for couples with particular preferences for the sex composition of their families. When couples desire k children of one sex and none of the other, the proportion of children in the completed family that are of the desired sex falls with increasing k. Constraints on total family size further reduce this proportion. When couples have a desire for a balanced composition of one boy and one girl, and when they have a preference for, say, a boy to be born first, they can expect a proportion of boys in the family that at first rises, and then falls, as sex preselection methods improve.

Family↗
PubMed1977

Preselective sex determination.

Preselective sex determination in ten consecutive pregnancies has been achieved by means of strict control over timing and technique of coitus which was combined with acidic or alkaline douching. Eight female and two male babies were born.

Acetates↗
PubMedDate not supplied

Sex preselection in New York City: who chooses which sex and why.

With its increasing success, sex preselection has become a matter of general concern, and interest in it is growing. Three aspects of sex preselection in New York City were considered. Who is choosing the sex? Which sex is being chosen? Why have the choices been made? In this investigation, 178 couples were studied and all 57 non-American couples chose boys; however, 120 American couples chose boys and girls with equal frequency depending upon the gender of the children at home. Non-American couples chose boys for economic and business reasons (40%), cultural reasons (30%), and personal reasons (30%). Sex preselection is valuable in preventing sex-linked genetic disorders. Many are fearful of a sudden change in sex ratios should sex preselection be successfully and inexpensively carried out.

Cultural Diversity↗
PubMed1992

Couples with exclusively female offspring have an increased probability of a male child after using male sex preselection.

The present study was undertaken to determine whether couples with one or more daughters and no sons had an increased probability of having a male child after using male sex preselection. The sex ratio of children born to couples after using 'protocol 3' (n = 70) or 'modified protocol 3' (n = 28) male sex preselection at one of 14 centres was determined. The normal approximation to the binomial distribution was used to determine significant differences between these sex ratios and the established sex ratio for children born to couples with one previous daughter and no sons. The sex ratios of both protocol 3 sex-preselected children (73.0%; P less than 0.0001) and modified protocol 3 sex-preselected children (86%; P less than 0.0001) were significantly different to the established sex ratio (control) for a current child born to parents with one previous daughter and no sons (50.1%). Couples with one or more daughters and no sons will have an increased probability of a male child after using male sex preselection.

Female↗
PubMedDate not supplied

Sex ratio of male sex preselected children born to couples with exclusively female offspring.

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 less than .00003). There were also significant differences between the sex ratio prior to modified 3 (0%) and after sex preselection (86%) (p less than .00003). Couples using male sex preselection do not have a decreased probability of a male child if they have had exclusively female children.

Female↗
PubMed1996

New advances in sex preselection.

OBJECTIVE: To review the current developments in the field of preconceptual sex selection and to discuss the moral dilemmas that accompany the scientific progress. DESIGN: A survey of the major publications on sex preselection. RESULTS: Examination of current methods of preconceptual gender selection revealed that in vivo methods such as timing of intercourse, the use of ovulation induction medications, and artificial insemination do not appear to affect the sex ratio to a clinically significant degree. In vitro separation of X- and Y-bearing spermatozoa by gradient techniques have been reported to alter significantly the sex ratio at birth. However, these trials were noncontrolled, and molecular biological techniques could not validate that these methods indeed change the Y- to X-bearing spermatozoa ratio sufficiently for clinical use. Nevertheless recent scientific advances have made highly reliable preconceptual sex selection possible by using preimplantation diagnosis or sperm separation by flow cytometry combined with IVF. At present, these methods have been used to avoid sex-linked disorders. Both involve the invasive procedure of IVF and thus are held by most as inappropriate for nonmedical indications. However, improvement in flow cytometry output of sexed spermatozoa might provide in the near future sufficient sorted gametes for artificial insemination. This technique then will provide an available noninvasive method of sexing for social purposes. CONCLUSIONS: Reliable preconceptual sex selection is currently possible only by preimplantation diagnosis, or sperm separation by flow cytometry combined with IVF. Both methods involve invasive procedures and are at present exclusively used for medical indications. It may be that in the near future, an improvement in flow cytometry output of sexed spermatozoa will provide sufficient sorted gametes for artificial insemination. In such a case, the medical community will be forced to take a stand, whether this reliable noninvasive method of sexing will be allowed for social purposes.

Cell Separation↗
PubMedDate not supplied

Sperm kinetics and morphology before and after fractionation on discontinuous Percoll gradient for sex preselection: computerized analyses.

The multiple-layer discontinuous Percoll density gradient centrifugation procedure is being used for gender selection and several reports suggested separation efficiencies of over 77%. The mechanism involved in the separation of X- and Y-bearing sperm using this method seems to be the difference in sperm head dimensions or motility but supporting data are inconsistent. The specific aims of the study were to evaluate the head dimensions of sperm at the upper and lower fractions after the 8-layer Percoll gradient procedure for sex preselection and to ascertain the kinematic parameters and tail lengths of sperm derived from the 2 separate Percoll fractions. Sperm cells were obtained from thawed donor specimens (N = 20) and were layered on top of the 8-layer discontinuous Percoll gradient, which ranged from 34 to 85% in increments of 7%. After centrifugation, the resuspended sperm cells derived from the upper and lower fractions of the Percoll gradient were analyzed on the Hamilton Thorn HTM-C analyzer for differences in sperm motility patterns and sperm head dimensions. Aliquots of sperm from the 2 fractions were fixed and stained using the Spermac stain, and the lengths of each sperm tail (N = 600) were measured on the HTM-C analyzer. Sperm derived from the bottom Percoll (X) fraction had a threefold higher (p < .05) percent motility when compared with sperm from the top (Y) fraction. Sperm derived from the bottom (X) fraction maintained the higher percentage motility after 24 h of incubation. The percent total progression, rapid progression, and hyperactivation were also significantly higher (p < .05) in sperm from the bottom (X) fraction. Similarly, the curvilinear (Vcl), average path (Vap) and straight line (Vsl) velocities were significantly faster in sperm (p < .05) from the bottom (X) fraction. In contrast, the percent linearity and straightness were significantly (p < .05) higher for the top (Y) fraction. Sperm from the bottom (X) fraction have shorter (p < .07) tail length (1.6% difference) when compared with sperm from the top (Y) fraction. Although the dimensions of the sperm head from the bottom (X) fraction were numerically greater than top fraction sperm, they were not significant (p > .05). The results suggest that bottom (X) fraction sperm derived from the 8-layer discontinuous Percoll gradient for sex preselection have higher motility, progression, and hyperactivation when compared with top (Y) fraction sperm. The bottom (X) fraction sperm have greater longevity in motility and have shorter tails, supporting earlier hypotheses of sex differences in sperm parameters. However, the present data do not support observations of differences in sperm head dimensions in sperm processed for sex preselection, and an inference of a larger sperm due to more chromosome material originating from the X chromosome cannot be made.

Cell Separation↗
PubMed1985

High long-standing fertilizing capacity of human sperm isolated for male sex preselection.

A method of separating a Y-enriched human sperm population for male sex preselection with a single-column, four-step, four-layer albumin gradient technique is presented. This technique provides an efficient separation of spermatozoa, good Y-enriched sperm motility, and high fertilization capacity of this fraction as tested by the zona-free hamster ova sperm penetration assay.

Cell Separation↗
PubMedDate not supplied

Characteristics of natural conceptual cycles occurring in a prospective study of sex preselection: fertility awareness symptoms, hormone levels, sperm survival, and pregnancy outcome.

A prospective study of sex preselection provided the opportunity to characterize the fertile menstrual cycle. We describe from 91 natural conceptual cycles, or sub-groups thereof, cervical mucus symptoms, basal body temperature (BBT) changes, hormonal characteristics, and the outcome of pregnancy. The cervical mucus symptoms defined a potential fertile period of 10 days' average length, with the "peak" mucus symptom occurring at a mean of day 15.5 of the cycle. A fertile period of 9 to 10 days was also indicated by pregnancies resulting from single acts of intercourse between -6 and +3 days from ovulation. The BBT chart was biphasic in 73 of 76 cycles. The duration of the LH surge as observed in early morning urine samples averaged five days, with the peak occurring 1.4 days after the onset. Considerable inter-subject variability was seen in the LH excretion levels. Hormone measurements of peripheral plasma during the luteal phase showed the first detectable presence of hCG between day 7 and day 13 after conception. Progesterone concentrations in the midluteal phase exceeded 20 nmol/L and tended to be higher than in a comparison group of nonfertile cycles, whereas the estradiol concentrations were similar in fertile and nonfertile cycles. The birth sex ratio favored males when intercourse preceded ovulation/fertilization by two days or longer. While this association was statistically significant, the number of pregnancies involved is too small to conclude that the relationship is real.

Adult↗
PubMed1993

Sex preselection through albumin separation of sperm.

OBJECTIVE: To determine if passage of sperm through columns of liquid albumin before their use in artificial insemination could affect the sex ratio at birth. DESIGN: Sperm were isolated by layering over columns of liquid albumin. The isolated fractions were inseminated into the uterus on the presumptive day of ovulation. SETTING: Patients were treated in 65 clinical practices (Sperm Centers) located both in this country (57) and abroad (8). PATIENTS: Individuals were self-selected by their desire to have a child of a specified sex. MAIN OUTCOME MEASURE: The sex of offspring resulting from the insemination of isolated sperm. RESULTS: Insemination with sperm isolated to enhance male sex preselection produced 71% and 76% males depending on the technique. Use of isolated sperm in women who were taking clomiphene citrate was associated with a 69% birth of females. CONCLUSIONS: Separation of sperm on columns of liquid albumin can affect the sex ratio at birth.

Cell Separation↗
PubMed1985

Sons and daughters--a sex preselection study.

A study designed to check the feasibility of a modified Shettles' sex selection technique was carried out in 73 women over four years. The results did not show a statistically significant difference from the sex ratios which resulted from uncontrolled intercourse.

Coitus↗
PubMed1977

Sex preselection.

There have been attempts to select the sex of a child prior to conception in both animals and humans. Centrifugation, microelectrophoresis and density gradient sedimentation have been used to separate X and Y sperm in animals. Only the latter technic has produced a change in sex ratio. In the human, timing of coitus or artificial insemination in relation to ovulation has been the popular method for influencing the sex of a child. This review suggests caution in accepting the claims of success for coital timing. Sperm bearing the Y chromosome can now be identified by quinacrine staining. Using this marker, Ericsson showed that when sperm are allowed to swin into columns of liquid albumin a high percentage of Y-bearing sperm are found in the most distal portion of the column. At this time it has not been shown whether the fraction enriched with Y sperm can produce a preponderance of males.

Animals↗
PubMed1989

Male sex preselection: swim-up technique and insemination of women after ovulation induction.

Insemination of women with sperm treated by the swim-up technique resulted in 81% male offspring. This was achieved even in women taking ovulation-inducing drugs, in whom the albumin gradient separation technique not only is not effective in male preselection but in which the female sex is favored. Confirmation of these initial data is needed as well as an investigation of the swim-up's efficacy of producing male offspring in women not taking ovulation-inducing drugs.

Clomiphene↗
PubMed1978

Sex preselection.

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Genetic Engineering↗
PubMed1989

Sex preselection in rabbits: live births from X and Y sperm separated by DNA and cell sorting.

Intact, viable X and Y chromosome-bearing sperm populations of the rabbit were separated according to DNA content with a flow cytometer/cell sorter. Reanalysis for DNA of an aliquot from each sorted population showed purities of 86% for X-bearing sperm and 81% for Y-bearing sperm populations. Sorted sperm were surgically inseminated into the uterus of rabbits. From does inseminated with sorted X-bearing sperm, 94% of the offspring born were females. From does inseminated with sorted Y-bearing sperm from the same ejaculates, 81% of the offspring were males. The probability of the phenotypic sex ratios differing from 50:50 were p less than 0.0003 for X-sorted sperm and p less than 0.004 for Y-sorted sperm. Thus, the phenotypic sex ratio at birth was accurately predicted from the flow-cytometrically measured proportion of X- and Y-bearing sperm used for insemination.

Animals↗