Let's get all our studies under one roof! I'll reserve the first several threads and then as we go, please feel free to post any interesting studies with a brief description of what they're about.
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Let's get all our studies under one roof! I'll reserve the first several threads and then as we go, please feel free to post any interesting studies with a brief description of what they're about.
Timing & Frequency
"Timing of Sexual Intercourse in Relation to Ovulation — Effects on the Probability of Conception, Survival of the Pregnancy, and Sex of the Baby"
http://www.nejm.org/doi/full/10.1056...99512073332301Quote:
Results
In a total of 625 menstrual cycles for which the dates of ovulation could be estimated, 192 pregnancies were initiated, as indicated by increases in the urinary concentration of human chorionic gonadotropin around the expected time of implantation. Two thirds (n = 129) ended in live births. Conception occurred only when intercourse took place during a six-day period that ended on the estimated day of ovulation. The probability of conception ranged from 0.10 when intercourse occurred five days before ovulation to 0.33 when it occurred on the day of ovulation itself. There was no evident relation between the age of sperm and the viability of the conceptus, although only 6 percent of the pregnancies could be firmly attributed to sperm that were three or more days old. Cycles producing male and female babies had similar patterns of intercourse in relation to ovulation.
"Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning."
http://www.ncbi.nlm.nih.gov/pubmed/9647580Quote:
In the context of ongoing debate over the determinants of sex ratio, the authors used data from a multinational study of pregnancies among natural family planning (NFP) users to investigate the association between timing of conception or follicular phase and length and the sex ratio at birth. They also explored whether a pregnancy's planned or unplanned status affects those associations. A multicenter, prospective study of pregnancies among women using NFP was conducted. The women maintained NFP charts of their conception cycles, recording acts of intercourse and signs of ovulation such as cervical mucus changes and basal body temperature. Charts were used to identify the most probable day of insemination relative to the day of ovulation and length of the follicular phase of the cycle. The sex ratio (number of males per 100 females) for 947 singleton births was 101.5, not significantly different from the expected value of 105. The sex ratio did not vary consistently or significantly with the estimated timing of insemination relative to the day of ovulation, with the estimated length of the follicular phase, or with the planned or unplanned status of the pregnancy. Study findings suggest that manipulating the timing of insemination during the cycle cannot be used to affect the sex of offspring.
"Length of the follicular phase, time of insemination,
coital rate and the sex of offspring" one attempt within fertile window sways pink, multiple attempts/short fertile windows (from earlier ov) sway blue
http://humrep.oxfordjournals.org/con...3/611.full.pdfQuote:
Evidence exists that less penetrable mucus selects for Y spermatozoa and that such selection decreases as mucus penetrability improves. Endogenous or hormonally-induced mucus penetrability improves over the late follicular phase and with the length of the follicular phase. However, there is also evidence that debris from previous inseminations reduces mucus penetrability for subsequent inseminations. Higher or increasing coital rates should therefore decrease mucus penetrability for later inseminations in both shorter and longer phases. When insemination occurs only once over the 6 or so days before ovulation, or when the coital rate is declining over that period, hormonally-induced improvements in mucus penetrability should result in male:female ratios which decline as the time of insemination approaches the end of the phase and as the phase is lengthened. If intercourse is frequent in the period before ovulation, there should be less or no association between time of insemination and sex of offspring.
However, while more frequent intercourse should raise the sex ratio among offspring in both longer and shorter phases, it should not alter the propensity for longer phases to be associated with a lower proportion of male offspring because the coital
rate affects both longer and shorter phases.
"Human sperm characteristics during frequent ejaculation:"
See the results section for fascinating tables showing sperm quantities, sperm concentration, and total semen drop after releasing every 8hrs because there is less seminal fluid with each release so close together
http://www.reproduction-online.org/c....full.pdf+htmlQuote:
Sperm concentration, morphology, DNA condensation and nuclear protein
pattern as well as sperm adenylate cyclase were evaluated in semen samples provided
by 7 volunteers every 8 h for 2 days. During the observation period, sperm concentration and total sperm number decreased but began to return towards normal after a 3\\x=req-\
day abstinence period. No increase in the proportion of immature sperm cells was
observed by light microscopy.
Total adenylate cyclase (EC 4.6.1.1) increased significantly per cell, due to an increase in the soluble component while the particulate component remained relatively constant. Microflow fluorometry revealed no consistent alterations in the DNA or nuclear protein distribution. We conclude that although a high frequency of ejaculation does not disturb the conventional measures of sperm integrity, such as DNA condensation, there are major changes in at least one biochemical measurement, the activity of soluble adenylate cyclase
"Within-subject variability of human semen in regard to sperm count, volume, total number of spermatozoa and length of abstinence"
http://www.reproduction-online.org/c....full.pdf+htmlQuote:
Summary. The within-subject variability of the semen sperm count (n), volume (v)
and the total number of spermatozoa (N) was studied on 220 ejaculates from 36 normal subjects after an abstinence of 7 days or less. For each of the three variables, the within-subject standard deviation , \g=s\,was practically proportional to the mean, \g=m\; the common value of the coefficient of variation \g=s\/\g=m\for all subjects was very high: 0\m=.\39for n, 0\m=.\28for v and 0\m=.\55for N. The 95% confidence intervals based on a single ejaculate were asymmetrical and very large, the lower and upper limits being
respectively 0\m=.\5\m=x\n and 2\m=.\3\m=x\n; 0\m=.\7\m=x\v and 1\m=.\8\m=x\v; 0\m=.\4\m=x\N and 2\m=.\9\m=x\N. The three semen characteristics for a given subject
were highly correlated with the length of abstinence: for an increase in abstinence of 1 day there were mean increments of 13 \m=x\106/ml for n, 0\m=.\4ml for v, and 87 \m=x\106 for N.
"The variations of human sex ratio at birth with time of conception within the cycle, coital rate around the time of conception, duration of time taken to achieve conception, and duration of gestation: A synthesis"
http://genderdreaming.com/forum/gend...hin-cycle.html (in the private member section)Quote:
There is a large research literature on the variation of human sex ratio (proportion of males at birth) with (1) time of insemination within the mother's fruitful cycle (TWC), (2) duration of gestation (DOG), (3) coital frequency, here called ‘coital rate’ (CR) and (4) duration of time taken to achieve conception in a period of risk (viz. in the absence of birth limitation methods) (TTC). The variation of sex ratio with each of these four variables has usually been treated as a discrete topic. Consider the four propositions that each of these sorts of variation exists. Here it is argued that these propositions entail one another to varying degrees, and that, for that reason, empirical failures to detect (at conventional levels of significance) one such form of variation (as e.g. with time to conception) should not justify rejecting the hypothesis that such variation exists until the whole network of propositions has been considered.
Diet
AKA the Oxford Study: "You are what your mother eats: evidence for maternal preconception diet influencing foetal sex in humans"
Link to study available in the dream members section: http://genderdreaming.com/forum/gend...earch-reports/Quote:
Facultative adjustment of sex ratios by mothers occurs in some animals, and has been linked to resource availability. In mammals, the search for consistent patterns is complicated by variations in mating systems, social hierarchies and litter sizes. Humans have low fecundity, high maternal investment and a potentially high differential between the numbers of offspring produced by sons and daughters: these conditions should favour the evolution of facultative sex ratio variation. Yet little is known of natural mechanisms of sex allocation in humans. Here, using data from 740 British women who were unaware of their foetus's gender, we show that foetal sex is associated with maternal diet at conception. Fifty six per cent of women in the highest third of preconceptional energy intake bore boys, compared with 45% in the lowest third. Intakes during pregnancy were not associated with sex, suggesting that the foetus does not manipulate maternal diet. Our results support hypotheses predicting investment in costly male offspring when resources are plentiful. Dietary changes may therefore explain the falling proportion of male births in industrialized countries. The results are relevant to the current debate about the artificial selection of offspring sex in fertility treatment and commercial ‘gender clinics’.
The Dutch study (studied diet in combination with Shettles timing)
Link to study available in the dream members section: http://genderdreaming.com/forum/gend...ing-study.htmlQuote:
These results show that both diet and timing methods increase the probability of a girl, the impact of the diet being the most pronounced. Table 3 and Figure 3 summarize the results of the 78 women who satisfied all basic protocol requirements. It shows a substantial success rate of 81% (n = 32), when both methods are applied correctly, whereas the success rate is only 24% (n = 46) if one or both of these methods are not applied correctly. If the diet is not followed correctly, the observed probability of a girl drops to 30%. The effect of correct timing of intercourse only, disregarding diet, is small (56%), whereas incorrect timing leads to 87% boys, which is in accordance with earlier hypotheses and studies (McSweeney, 1993). The diet obviously has a larger impact, since the effect of correct diet only, disregarding timing of intercourse, is 73%.
Folic acid: influence on the outcome of pregnancy
http://www.ajcn.org/content/71/5/1295S.longQuote:
In addition to increasing the number of recognized conceptions, supplementation with folic acid–containing multivitamins significantly increased the rate of multiple births (74). The number of female births was marginally greater among the folic acid–supplemented women (P = 0.18). In an analysis that included both singleton and multiple births, there was a small but statistically significant excess of low-birth-weight infants in the folic acid–supplemented group than in the trace mineral group (75).
Supplements - sex ratio in rats
Food restriction or decreasing the ratio of Sodium and Potassium to Calcium and Magnesium in the diet of female rats before conception favored the production of female offspring.
http://onlinelibrary.wiley.com/doi/1...30406/abstract
Supplements - sex ratio in rats (another)
http://onlinelibrary.wiley.com/doi/1...30406/abstractQuote:
In group NaK, under sodium and potassium diet, 23 rats out of 24 became pregnant which delivered 164 offspring. Their gender was 91 male and 73 female (55.5% male and 44.5% female). In group CaMg, under calcium and magnesium diet, all of the 24 rats became pregnant and delivered 163 offspring. From all pregnant rats, 66 male and 97 female rats were born (40.5% male and 59.5% female). Finally, in the control group (group C) all of the 24 rats became pregnant and delivered 147 offspring. From all pregnant rats, 72 male and 75 female rats were born (49% male and 51% female).
Change in mother's condition at time of conception
http://rsbl.royalsocietypublishing.o...t/3/4/395.fullQuote:
We used condition measures before and after conception to measure the change in condition around conception in individual mothers. The relationship with sex ratio was substantially more extreme than previously reported: 3% of females losing condition gave birth to a son, whereas 80% of those females that were gaining condition gave birth to a son. Change in condition is more predictive of sex ratio than actual condition, supporting previous studies, and shows the most extreme variation in mammals ever reported.
Influences of maternal weight on the secondary sex ratio of human offspring
http://humrep.oxfordjournals.org/content/19/2/442.fullQuote:
RESULTS: The secondary sex ratio of mothers in the lowest quartile of pre‐pregnancy body weight (<54.6 kg) was lower than that of the other three quartiles (0.497 versus 0.525; P < 0.01). In contrast, the sex ratio of children born by the women in the highest quartile of weight gain during pregnancy appeared lower than that of the first three quartiles (0.493 versus 0.516; P = 0.054). CONCLUSIONS: A low pre‐pregnancy weight and a greater weight gain during pregnancy are both associated with a reduced secondary sex ratio. These data indicate that in women with non‐optimal reproductive/metabolic conditions, a greater attrition is exerted on male than on female offspring.
Effect of maternal stress on fertility and sex ratio: A pilot study with rats.
http://psycnet.apa.org/index.cfm?fa=...1974-04408-001Quote:
Based on the theory that stress accounts for the high proportion of daughters born to schizophrenic women, the relation of maternal stress to fertility and sex ratio was examined in 24 female virgin Long-Evans hooded rats. 12 Ss were stressed in wire-screen cocoons for 4 hrs/day for 1 wk before conception. The influence of the father on sex ratio and fertility was controlled by mating the same males (n = 4) with stressed and with unstressed females. Stressed females gave birth to significantly fewer males and significantly smaller litters than unstressed controls. It is concluded that the male zygote and fetus are evidently more vulnerable to stress than their female counterparts. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)
Mother's occupation and sex ratio at birth
http://www.biomedcentral.com/content...458-10-269.pdfQuote:
Results: Women in job types that were categorized as "high stress" were more likely to give birth to daughters,
whereas women in job types that were categorized as "low stress" had equal sex ratios or a slight male bias in offspring.
We also investigated whether maternal age, and her partner's income could be associated with reversed offspring sex
ratio. We found no association between mother's age, her partner's job stress category or partner income on child sex.
Interpregnancy intervals, high maternal age and seasonal effects on the human sex ratio and implantation
http://humrep.oxfordjournals.org/con...1/1/7.full.pdf
Interpregnancy weight gain and the male-to-female sex ratio of the second pregnancy: a population-based cohort study.
http://www.ncbi.nlm.nih.gov/pubmed/17889856Quote:
OBJECTIVES:
To investigate whether interpregnancy maternal weight change (difference between body mass index [BMI] at the first antenatal visit of the second pregnancy and BMI at the first antenatal visit of the first pregnancy) or changes in smoking status between pregnancies is related to the sex ratio of the second pregnancy.
Influence of moonlight on the birth of male and female babies.
http://www.ncbi.nlm.nih.gov/pubmed/16295726Quote:
Effects of full moon and no moon on the birth of male and female offspring were studied in Indian Couples of the age group 20 to 40 years. It was observed that 42 wives who were conceived within 24 hours of ovulation at full moon gave birth of 40 male and 2 female babies. On the other hand 40 women conceived on the day of ovulation 3 days prior to full moon gave birth of 13 male and 27 female babies. But only 5 women conceived on no moon, all of them gave birth of female babies.
reserved 4
reserved 5
finally :giggle:
will get onto this in a few hours when DS is in bed!
ETA - actually, it'll be tomorrow now, going to have an early night even though it's new year!
Atomic, is that the sort of thing you were imagining? or just a list of links with no quotes?
I like that Rainbow, it gives an overview which means you don't have to read through the entire (sometimes almost incomprehensible!) study!
thanks, Zana... need to track down some of the original FGD result and Dutch studies now
The full PDF from the Dutch study is in the Swaying Research Forum and I typed out the details of the FGD in a couple of different posts.Quote:
Originally Posted by rainbowflower
thanks, those FGD links are in that forum too? will check them out :)Quote:
Originally Posted by nuthinbutpink
Well, I was more envisioning a shorter description of what the study was about but that works too and actually may save some time having to type a description. We may have to start a second thread tho because those things are kinda large. Much more helpful than the "other site" list of links and a great idea to post the paragraphs.
Thank you so much for adding them!
I have not been able to find FGD links that were translated except on very rare occasions.http://www.ncbi.nlm.nih.gov/pubmed/7163616 I do have this link which did not support the FGD, done by other researchers in the same time period.Quote:
Originally Posted by rainbowflower
feel free to edit/tweak/shrink them as always, they're only the abstract/conclusion bit copied out ;)
I have the book. The text I typed out in the forum is directly from the book.Quote:
Originally Posted by atomic sagebrush
Great idea AS!
hmm I seem to have missed all the links for hormones affecting swaying??
I don't seem to be able to edit these posts anymore, so the clomid study will need adding:
http://www.ncbi.nlm.nih.gov/pmc/arti...00038-0021.pdf