Truth Behind Kyle XY? Gestation time vs Intelligence?

May 12, 2009 3:34 PM

Is there any truth behind the premise of the TV show Kyle XY? That prolonged gestation leads to higher intelligence?

Are there any studies comparing IQ to gestation length? Are there even myths, or superstitions behind this idea, or did the shows creators completely make it up?

posted by GregX3 to science & nature (3 comments total)

Sort of. Longer gestation is linked to larger babies, and many studies have shown low birth weight babies (those born weighing less than 2500 grams) have lower IQ test scores at school age - and the smaller the babies at birth, the larger the IQ deficit.

I've seen other studies referred to saying the same thing, that larger babies tend to end up with higher IQs and better immune systems. It's worth pointing out that this is only a tiny difference, 4.6 IQ points in boys and 2.8 points in girls.

There's also the effect of whether they're the firstborn: results suggest that earlier born children have higher IQs, although this seems to be nurture instead of nature. Again, the difference is tiny.
posted by metaBugs at 4:13 PM on May 12

I worked with someone who was significantly late in exiting the womb; this was only of note because she was apparently born with hugely long fingernails. Since one has no idea what her IQ would have been had she made her entrance earlier, can't speculate on that.

Some of the elder bits of the Greek pantheon had a secondary gestation, being swallowed by their father Cronus and lurking in their stomach until Zeus poisoned him so he vomited up the gods. However, the Greek gods aren't big on intelligence unless it's cunning used to enact vengeance, so I don't think they're a good model.
posted by Coobeastie at 4:14 PM on May 12

You can find articles relating to this through google scholar*. First hit, for example, was this (1966 study), while selecting "recent articles" turns up this (2006 study).

*Just be aware that many of these articles won't be available to you outside of a university.

At first glance, it appears that there is some correlative evidence that low birth weight/length is associated with reduced intellectual performance. But most studies appear to be focused on comparing shortened gestation times to normal gestation times rather than comparing shorter vs. longer gestation times within the normal range.

As for abnormally long gestation times, the reverse is probably true. From the 1966 study:
Prolonged gestation has been suggested as a cause of cerebral damage and consequent intellectual impairment, but no data bearing on this issue appear to have been published.

I can't access the entire paper from here, so I can't see what their findings were (this is why we invented abstracts, dammit!), but I'm sure you can find more recent studies through google scholar. I really doubt that any gestation time that falls outside of the normal range will have any benefits. Quite the opposite in fact.
posted by kisch mokusch at 4:19 PM on May 12