sex ratio linked to mothers age when she began menstrating.

I was 12.5 and have GBG.

WOW that is fascinating. The thing that was the most interesting was that they found a correlation between low fertility rate and more girls born which fits in exactly with the idea that low fertility = pink and optimal fertility = blue.

Thank you so much for sharing!!

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Originally Posted by purplepoet20

Still confused as to what I should have based on that... I started on my 12th birthday and have had 3 male births. My stepmom was 16 and had B, G, G. My biomom was 14 and had G, B, G, G, B. My dads mom was 18 and had G, B, B, B, B. My moms mom was about 17 and had G, G, G, B, B, B, G, B, G (all a year apart but 3B's were stillborn).

So with this research at what age do I get a girl?

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Look at it this way instead. If you have optimal fertility, you will have more boys regardless of when you started your period. If you have lower fertility, you will have more girls regardless of when you started your period. There is nothing magic about the age of menarche, it's probably what it represents. People whose reproductive hormones are out of whack for any reason and are less fertile are BOTH more likely to start their periods at younger/older ages and also to be less fertile. Does that make sense???

I started at just barely 12 and my mom (has 2 G 1 B) started at 15 so it does seem to hold true for us.

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Originally Posted by skrimpy

this is interesting. The abstract was a little confusing to me, too. Maybe somebody who knows that lingo better can write it out in plain English?

I can add mine and my mom's info:

My mom started at 11 and had B (stillborn), G, B and many, many miscarriages where gender was unknown
I started at 14 and had G, B, B, B, and G on the way now.

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I'll try to translate.

"Getting your period at a young age is a risk factor for breast and ovarian cancer and also a higher rate of miscarriage. This study was done to see if there is a link between starting your period young and the gender of your kids."

"We studied the gender of 21,208 babies born to 10,847 women from ages 22-54, the midpoint of which was 37 years old, and compared this info with the age the mom was when she got her period and also compared this info to the number of babies each woman had to judge her fertility."

"More girls were born, 80 boys for every 100 girls (note - this is a MAJOR statistical variation and the sample size was HUGE, meaning this study carries more weight than some other studies that have been done) to women who started their periods when they were 9 years old. More girls than boys were born until women started their periods at age 12 at which point the ratio was slightly higher than 100 boys born for every 100 girls. (note - just ignore all the OR stuff, it's confusing and doesn't add anything to the info) The most boys were born to women who started their periods at age 14, with 110 boys being born for every 100 girls (again, a major variation) and then the ratio of boys to girls began to decline again, reaching 100 boys to 100 girls to women who began their periods at 17 years old. The fertility index of those women who started their periods at ages 9-11 was also low, meaning they had fewer children overall.

"Conclusion - women who start their periods at any time outside the normal range of ages 12-14, but especially those who start at a younger age, are more likely to conceive daughters."

Interesting! I started at 11 and have two boys.

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Originally Posted by atomic sagebrush

WOW that is fascinating. The thing that was the most interesting was that they found a correlation between low fertility rate and more girls born which fits in exactly with the idea that low fertility = pink and optimal fertility = blue.

Thank you so much for sharing!!

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Your welcome :)

Thank you for rewriting that Atomic - makes much more sense! Very interesting :)