Some Statistics On What The Sexual Rebellion Wraught

I’m always complaining of statistics gone awry, but a constant diet of bad news can lead to bad things, like a desire to listen to NPR or to use PowerPoint. So here today is a good example from the Scientific American (the source itself is a surprise) article “Is the Rise in Twin Births Cresting? Fertility procedures have pushed multiple births higher, prompting policy changes“.

The graph which appears above is a shrunken version of the original; click through to SA for a better view.

It shows through time the estimated number of pregnancies per 1,000 resulting in twins broken out by a few countries. The numbers are estimates, because (of course) not all births are everywhere counted. No uncertainty in the lines is shown, which is a minor flaw, and mostly harmless as long as it is kept in mind that there is a lingering plus-or-minus to the numbers.

The numbers are one thing, their causes another. The cause won’t be in the numbers per se, which is why it is good there are no statistical tests or wee p-values to say why any particular line took the values it did. Take a look at the U.S. line for an example. It shows a peak right before 1920. The explanation offered is “Twinning rates spiked briefly, in part because especially fertile women—who have twins more often—were more likely to conceive during a spouse’s short visit home from war.”

The only surprise is they let slip the word spouse. Skip it. Is that the real reason, a.k.a. cause, of the blip? It sure sounds plausible as an explanation. But is it true? The data itself are silent on this question; hence hypothesis testing is useless. We can look outside the data, as the authors have done, but it is not proof. However, given our knowledge of human nature, of the war, and of the culture circa 1918, we can say the explanation is likely true.

Remembering that the older the data, the greater the plus-and-minus, elsewhere in the West, rates were on their way down gradually from 1920 through the 1950s. Modernity was tightening its grip (a causal guess). Except in Ireland, which had a bit of a bounce. Any Ireland historians care to take a stab?

The sexual “revolution”, or rather the sexual rebellion, is, of course, embedded in stream of Realityphobia that has seen a decided strengthening since around the time of the French Revolution. Like calls to like. But the 1960s saw outright revolt. Just look at that plunge! We all know, and knew, the causes here; what’s new is that some of them can be roughly quantified.

Then comes 1978: “First IVF Baby.” As that bit of technology was disseminated, rates began to rise again. But also occurring were mothers starting their broods at later ages. For other reasons (causes), women unaided by chemicals and surgery have more twins at later ages. That mothers were waiting was partly due to sexual rebellion and partly because of Modernity (another causal guess). You can see the rest.

Japan is different. Before World War II, Japan was very poor and had low birth rates, not just low numbers of twins. Food was limited, especially in the countryside. Notice the grey line that connects Japan from about 1938, when the loot taken from China were already flowing back to the homeland, and from 1970 when data was being collected again. The grey line indicates a steady increase. This is unlikely, especially given what happened in 1944 and 1945. The danger of extrapolation!

Now take a look at the lower-right-hand graph, which shows Triplets and Higher birth rates. An amazing picture! The rapid acceleration follows the IVF/late-birth twins line. But what explains the plunge after about 2000?

Killing. I believe the euphemism is prenatal herd-thinning. No, wait. It’s reduction. Doctors don’t like women having triplets-plus (or even twins in many cases) and so recommend killing the excess over two. The strategy is first drug up the older mothers, who spent too many years in a cubicle building PowerPoint “decks”, then eliminate the excess IVF successes. Charming.

Last, there are predictions for the reason in changing rates of twins; either increasing maternal age or increasing fertility treatment use. Of course, in any individual woman the reason may be one or the other or both or neither. So really these are crude inter-country summaries, and thus only of limited use. But predictions are the way to go (whether these are really model-parameter estimates and not predictions, I didn’t check).


  1. Gary

    Wraught? Or Wrought?

  2. Joy

    Who believes in that story? Women were being rebellious! That is just more story telling. Each woman did what she did and had reasons or none for doing what she did. There was no such movement of rebellion.

    Damn those females who spoilt things for whom? For men of the cloth who gave up sex altogether? Or for God? Is God angry about this? Or are men and a few unthinking women depressing themselves with dark imaginings about the sins of women? Probably. So I give you something to be depressed about.

    Reproductive medicine is an array of different things. It is not all about IVF and surplus “baby killing” although you’d be forgiven for thinking so if you listened to fanatics on abortion.

    The figures are scanty as the swimming ‘costumes’ on a Latin country’s Beach if it is to be claimed that they show anything!

    Where is Scotland and Northern Ireland? Right there one starts to suspect the source of the data as being politically motivated.

    As to going away to war, most of the countries on that list weren’t involved in the war. They were neutral, aka cowards.

    Ireland, who allowed Hitler to moor their subs curing the war, did not leave, romantically, for war. They kept making babies in secret. Those Irish eyes were smiling.

    Ireland at that stage had a ‘glut of babies’, not official statistics you understand, in which they found lucrative baby laundering businesses selling babies.
    That occurred without the knowledge or consent for adoption of the mothers. It was the English change of attitude which saw the end to the practice as so many young people from Ireland simply came and still come to London for a life and a job. So they are brought kicking and screaming into the modern age of not baby laundering when those Irish folk grow up and retire back to Ireland with their new ideals and ideas of what is right and what is acceptable. It was the influence of England which saw an end to the baby factories.

    This was kidnapping of mother and baby,
    It was human trafficking of babies,
    it was slavery, of mothers,
    it was cruel and wicked punishment for no crime but for sin.
    It was cruel and wicked punishment of babies.
    Mothers were put through hell on earth for the gratification of nuns on behalf of the church who played God and thought that God would be pleased.

    The babies grew up thinking their mothers didn’t want or love them and gave them away with the same casual abandonment with which they had been conceived. Such was the dark imagination of the nuns when considering the actions and sins of other women. Many of those babies knew, if they were adopted by Catholics, that they weren’t loved and knew all about the sin of their mother. So the story continues to be told. Children of unmarried mothers are loveless and are therefore less lovable. I’ve seen it written plainly and implied here by commenters.

    Always it is the sexual sin of others which concerns people with strong church ties. Their own sins are never counted in the statistics.

    For Irish social history See Philomena. The tip of the iceberg. You have to admire their entrepreneurial spirit. There was nothing holy about them.

  3. Joy

    30,000 babies during the era of the Magdalene laundries which existed for ninety years and the last one closed in the 90’s.

    The entire fabric of Irish society was involved and has since been acknowledged by the Irish state as being culpable for the Magdalene laundries.
    See also the magdalene sisters in ten parts.

    When my fellow students complained about the nuns I thought they were exaggerating. I have only learned of this going on in the last year.
    I suspected there was something there and now I find it’s true.
    So when i was visiting the grave of one of the adopted babies who reached 21 in the 9o’s I had no idea.
    “No funeral no grave no life.”
    Let babies be born. Lots of them. In and out of wedlock as needs be.

  4. Ye Olde Statistician

    Here is a graph of the US birth rates only, without regard to twins or triplets. Annual numbers were posted starting only in 1909. You will note that the birth rate icicled sharply in 1919. I call this the “Faithful Sweetheart Effect” due to the guys being off in France in 1918. Then in 1920-21, the birth rate spikes up, which I call the “Johnny Comes, Marching Home Effect.” The intriguing thing is that after this perturbation, the birth rate settles onto where a natural cycle would have taken it had there been no icicle or spike in the first place.

    Let’s see if the graph appears:

    The icicle-spike pattern reappears in WW2, only bigger and longer as more boys were away for a longer time. It’s interesting to note that the birth rates were rebounding from the depression levels before this happened. That is, the Boom was not a consequence of the War, but something that was in the cards, so to speak, and the War interrupted.

    The third spike corresponds, so far as I can tell, to the Summer of Love (or rather one year later). The elevated birth rates that followed were a consequence of the Baby Boomers reaching child-bearing age. One of these days I plan to bring the chart up to date just to see what’s happened since the 90s.

    The overall impression is that of a cycle riding on the back of a long-term declining trend (possibly a decaying exponential). The trend can be discerned in birth rates estimated from Census records going back to 1820. (Earlier census records were destroyed in the War of 1812.)

    The number of children two parents have is proportional to the amount of resources available to them (R), the amount required to sustain the parents in their niche (P), and inversely proportional to the unit cost of raising a child in that niche (C). Hence: N ? (R-P)/C. So as society becomes less rural and more urban, children become more expensive. (Another kid on the farm is an asset and can feed the chickens or slop the hogs; but another kid in the city can’t do too much in the office or factory to contribute to income.) So urban families tend on the average to have fewer children. Hence, the underlying downward trend.

  5. Rob

    The multiple birth numbers given here are US only, but in the UK the regulators (forgotten their acronym) banned insertion of more than two fertilised embryos at a time. It got a lot of flack at first – with some doctors ignoring the rule – but I haven’t heard much for a while. I don’t know any rules in the US, but it may also be that the success rate of implantation is going up so doctors now insert fewer embryos in the first place.

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