SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Fertility

295

If humans ever start to live permanently in space, assisted reproductive technology using preserved spermatozoa will be important for producing offspring; however, radiation on the International Space Station (ISS) is more than 100 times stronger than that on Earth, and irradiation causes DNA damage in cells and gametes. Here we examined the effect of space radiation on freeze-dried mouse spermatozoa held on the ISS for 9 mo at -95 °C, with launch and recovery at room temperature. DNA damage to the spermatozoa and male pronuclei was slightly increased, but the fertilization and birth rates were similar to those of controls. Next-generation sequencing showed only minor genomic differences between offspring derived from space-preserved spermatozoa and controls, and all offspring grew to adulthood and had normal fertility. Thus, we demonstrate that although space radiation can damage sperm DNA, it does not affect the production of viable offspring after at least 9 mo of storage on the ISS.

Concepts: Gene, Male, Reproduction, Female, Sperm, Fertility, Spermatozoon, International Space Station

277

Human menopause is an unsolved evolutionary puzzle, and relationships among the factors that produced it remain understood poorly. Classic theory, involving a one-sex (female) model of human demography, suggests that genes imparting deleterious effects on post-reproductive survival will accumulate. Thus, a ‘death barrier’ should emerge beyond the maximum age for female reproduction. Under this scenario, few women would experience menopause (decreased fertility with continued survival) because few would survive much longer than they reproduced. However, no death barrier is observed in human populations. Subsequent theoretical research has shown that two-sex models, including male fertility at older ages, avoid the death barrier. Here we use a stochastic, two-sex computational model implemented by computer simulation to show how male mating preference for younger females could lead to the accumulation of mutations deleterious to female fertility and thus produce a menopausal period. Our model requires neither the initial assumption of a decline in older female fertility nor the effects of inclusive fitness through which older, non-reproducing women assist in the reproductive efforts of younger women. Our model helps to explain why such effects, observed in many societies, may be insufficient factors in elucidating the origin of menopause.

Concepts: Human, Male, Reproduction, Female, Demography, Sex, Fertility, Evolutionary psychology

265

The rapid spread of Zika virus in the Americas and current outbreak of microcephaly in Brazil has raised attention to the possible deleterious effects that the virus may have on fetuses.

Concepts: Fertility, Abortion, São Paulo, German language, Americas, Latin America, Hydrops fetalis, Rh disease

184

An important problem in reproductive medicine is deciding when people who have failed to become pregnant without medical assistance should begin investigation and treatment. This study describes a computational approach to determining what can be deduced about a couple’s future chances of pregnancy from the number of menstrual cycles over which they have been trying to conceive. The starting point is that a couple’s fertility is inherently uncertain. This uncertainty is modelled as a probability distribution for the chance of conceiving in each menstrual cycle. We have developed a general numerical computational method, which uses Bayes' theorem to generate a posterior distribution for a couple’s chance of conceiving in each cycle, conditional on the number of previous cycles of attempted conception. When various metrics of a couple’s expected chances of pregnancy were computed as a function of the number of cycles over which they had been trying to conceive, we found good fits to observed data on time to pregnancy for different populations. The commonly-used standard of 12 cycles of non-conception as an indicator of subfertility was found to be reasonably robust, though a larger or smaller number of cycles may be more appropriate depending on the population from which a couple is drawn and the precise subfertility metric which is most relevant, for example the probability of conception in the next cycle or the next 12 cycles. We have also applied our computational method to model the impact of female reproductive ageing. Results indicate that, for women over the age of 35, it may be appropriate to start investigation and treatment more quickly than for younger women. Ignoring reproductive decline during the period of attempted conception added up to two cycles to the computed number of cycles before reaching a metric of subfertility.

Concepts: Pregnancy, Fertility, Menstrual cycle, Endometrium, Progesterone, Conditional probability, Bayes' theorem, Pregnancy test

183

Although antibiotics are widely used during pregnancy, evidence regarding their fetal safety remains limited. Our aim was to quantify the association between antibiotic exposure during pregnancy and risk of spontaneous abortion.

Concepts: Pregnancy, Fetus, Obstetrics, Fertility, Abortion, Miscarriage, 1960s music groups

171

BACKGROUND: Malaysia has relatively liberal abortion laws in that they permit abortions for both physical and mental health cases. However, abortion remains a taboo subject. The stagnating contraceptive prevalence rate combined with the plunging fertility rate suggests that abortion might be occurring clandestinely. This qualitative study aimed to explore the experiences of women and their needs with regard to abortion. METHODS: Women from diverse backgrounds were purposively selected from an urban family planning clinic in Penang, Malaysia based on inclusion criteria of being aged 21 and above and having experienced an induced abortion. A semi-structured interview guide consisting of open ended questions eliciting women’s experiences and needs with regard to abortion were utilized to facilitate the interviews. Audio recordings were transcribed verbatim and analyzed thematically. RESULTS: Thirty-one women, with ages ranging from 21–43 years (mean 30.16 +/-6.41), who had induced surgical/medical abortions were recruited from an urban family planning clinic. Ten women reported only to have had one previous abortion while the remaining had multiple abortions ranging from 2–8 times. The findings revealed that although women had abortions, nevertheless they faced problems in seeking for abortion information and services. They also had fears about the consequences and side effects of abortion and wish to receive more information on abortion. Women with post-abortion feelings ranged from no feelings to not wanting to think about the abortion, relief, feeling of sadness and loss. Abortion decisions were primarily theirs but would seek partner/husband’s agreement. In terms of the women’s needs for abortion, or if they wished for more information on abortion, pre and post abortion counseling and post-abortion follow up. CONCLUSIONS: The existing abortion laws in Malaysia should enable the government to provide abortion services within the law. Unfortunately, the study findings show that this is generally not so, most probably due to social stigma. There is an urgent need for the government to review its responsibility in providing accessible abortion services within the scope of the law and to look into the regulatory requirements for such services in Malaysia. This study also highlighted the need for educational efforts to make women aware of their reproductive rights and also to increase their reproductive knowledge pertaining to abortion. Besides the government, public education on abortion may also be improved by efforts from abortion providers, advocacy groups and related NGOs.

Concepts: Pregnancy, Birth control, Family planning, Human rights, Fertility, Abortion, History of abortion, Paternal rights and abortion

169

It is known that sperm samples from recurrent pregnancy loss (RPL) couples have an increase in their sperm DNA fragmentation (SDF), but no studies have been performed in order to identify differences between single stranded SDF (ssSDF) and double stranded SDF (dsSDF) in these patients. This could be relevant because the type of DNA damage could have different effects. Semen samples were classified attending their clinical status: 25 fertile donors and 20 RPL patients with at least two unexplained first trimester miscarriages. SDF was analysed using alkaline and neutral Comet assay, SCD test and pulsed-field gel electrophoresis (PFGE), and ROC analysis including data from 105 more infertile patients (n = 150) was performed to establish predictive threshold values. SDF for alkaline and neutral Comet, and the SCD test was analysed in these categories of individuals. Data revealed the presence of two subgroups within fertile donors. The values obtained were 21.10±9.13, 23.35±10.45 and 12.31±4.31, respectively, for fertile donors with low values for both ssSDF and dsSDF; 27.86±12.64, 80.69±12.67 and 12.43±5.22, for fertile donors with low ssSDF and high dsSDF; and 33.61±15.50, 84.64±11.28 and 19.28±6.05, for unexplained RPL patients, also showing a low ssSDF and high dsSDF profile. This latter profile was seen in 85% of unexplained RPL and 33% of fertile donors, suggesting that it may be associated to a male risk factor for undergoing RPL. ROC analysis regarding recurrent miscarriage set the cut-off value at 77.50% of dsDNA SDF. PFGE for low ssSDF and high dsSDF profile samples and positive controls treated with DNase, to induce dsDNA breaks, showed a more intense band of about 48 kb, which fits the toroid model of DNA compaction in sperm, pointing out that some nuclease activity may be affecting their sperm DNA in RPL patients. This work identifies a very specific SDF profile related to the paternal risk of having RPL.

Concepts: DNA, Gene, Pregnancy, Genetics, Fertility, Abortion, Miscarriage, Habitual abortion

168

Textbooks on evolutionary psychology and biology cite the case of the Sharifian Emperor of Morocco, Moulay Ismael the Bloodthirsty (1672-1727) who was supposed to have sired 888 children. This example for male reproduction has been challenged and led to a still unresolved discussion. The scientific debate is shaped by assumptions about reproductive constraints which cannot be tested directly-and the figures used are sometimes arbitrary. Therefore we developed a computer simulation which tests how many copulations per day were necessary to reach the reported reproductive outcome. We based our calculations on a report dating 1704, thus computing whether it was possible to have 600 sons in a reproductive timespan of 32 years. The algorithm is based on three different models of conception and different social and biological constraints. In the first model we used a random mating pool with unrestricted access to females. In the second model we used a restricted harem pool. The results indicate that Moulay Ismael could have achieved this high reproductive success. A comparison of the three conception models highlights the necessity to consider female sexual habits when assessing fertility across the cycle. We also show that the harem size needed is far smaller than the reported numbers.

Concepts: Sexual intercourse, Human, Male, Reproduction, Female, Organism, Sex, Fertility

168

Background Ovarian aging and cytotoxic treatments are the most common causes for fertility loss in women. With increasing numbers of young female survivors following cytotoxic cancer treatments, the issue of fertility preservation has assumed greater importance. Methods We review the literature on the causes of female fertility loss as well as the recent advances in fertility preservation options and strategies that might be of interest to oncologists. Currently, several methods and techniques exist for fertility preservation of female patients with cancer including embryo freezing, ovarian protection techniques, oocyte cryopreservation, ovarian tissue cryopreservation followed by autotransplantation, and recently in vitro culture of ovarian tissue, follicles, and oocytes. Each method or technique has advantages and disadvantages related to current success rate, required delay in cancer treatment, sperm requirement, and risk of reintroducing cancer cells. Results To date, embryo freezing is the only established method successfully and widely used for fertility preservation of female patients with cancer. The other methods are promising but still considered experimental. Conclusion Patient awareness, physician knowledge, early counseling, costs management, international registry, interdisciplinary networks, and research development are necessary to improve the current care in the field of female fertility preservation.

Concepts: Cancer, Oncology, Fertility, Spermatozoon, Zygote, Cryobiology, Cryopreservation, Oocyte cryopreservation

168

BACKGROUND: Noninvasive prenatal detection of common fetal aneuploidies with cell-free DNA from maternal plasma has been achieved with high-throughput next-generation sequencing platforms. Turnaround times for previously tested platforms are still unsatisfactory for clinical applications, however, because of the time spent on sequencing. The development of semiconductor sequencing technology has provided a way to shorten overall run times. We studied the feasibility of using semiconductor sequencing technology for the noninvasive detection of fetal aneuploidy.METHODS: Maternal plasma DNA from 13 pregnant women, corresponding to 4 euploid, 6 trisomy 21 (T21), 2 trisomy 18 (T18), and 1 trisomy 13 (T13) pregnancies, were sequenced on the Ion Torrent Personal Genome Machine sequencer platform with 318 chips. The data were analyzed with the T statistic method after correcting for GC bias, and the T value was calculated as an indicator of fetal aneuploidy.RESULTS: We obtained a mean of 3 524 401 high-quality reads per sample, with an efficiency rate of 77.9%. All of the T21, T13, and T18 fetuses could be clearly distinguished from euploid fetuses, and the time spent on library preparation and sequencing was 24 h.CONCLUSIONS: Semiconductor sequencing represents a suitable technology for the noninvasive prenatal detection of fetal aneuploidy. With this platform, sequencing times can be substantially reduced; however, a further larger-scale study is needed to determine the imprecision of noninvasive fetal aneuploidy detection with this system.

Concepts: Pregnancy, Infant, Embryo, Fetus, Uterus, Fertility, Abortion, Aneuploidy