My dissertation advisor Lee Willerman used the data for a couple of his papers. I think Eric Turkheimer used it in his dissertation.
One thing Lee told me he found but never published was that c-sectioned kids had higher IQs. Pretty sure he’d have thought to control for mothers’ IQ. He thought it might represent a difference in birth canal trauma.
I went and looked for the WISC FSIQ. In the basic OLS specification that just controls for sex, race, birth order, and maternal age, I got -1.29 IQ points for a C-section (p = 0.002). With a control for SES in the form of education years and the SEI score, that went to -0.92 (p = 0.018). In the mother FE that just controls for sex and birth order, the result was +1.53 (p = 0.12).
In an OLS with demographics, SES, birth weight, gestational age, and Apgar total, I get -0.88 (p = 0.030). Mother FE with birth weight is +1.51 (p = 0.12) and with added gestational age and Apgar total, it's +0.77 (p = 0.47).
So, I'd say, not much evidence for C-section benefits here.
Incidentally, I also checked out whether head circumference predicted being a C-section birth in this cohort, and the answer is no! Head circumference at birth was 33.66 cm for vaginal births and 33.60 for C-sections and there seems to be an elevated risk of C-section for both extremely small- and extremely large-headed babies. Within families with discordant births, there's no gap either, and power is too low to detect if there's a difference between extremes.
This is a good cohort to test this in because, in the '60s, C-sections were driven by obstetric emergencies like malpresentation, fetal distress, prior C-section, etc., rather than size measures per se.
Slightly off topic, but what was your process of actually finding, scanning, and digitizing the microfiche? I'm sure this could be done with other datasets, very cool work.
The people who scanned it in did all the physical work of moving all the microfiche into the scanners and uploading it. I took what they uploaded in various formats, aligned it, OCR'd it, and cleaned it up.
My dissertation advisor Lee Willerman used the data for a couple of his papers. I think Eric Turkheimer used it in his dissertation.
One thing Lee told me he found but never published was that c-sectioned kids had higher IQs. Pretty sure he’d have thought to control for mothers’ IQ. He thought it might represent a difference in birth canal trauma.
Good question!
I went and looked for the WISC FSIQ. In the basic OLS specification that just controls for sex, race, birth order, and maternal age, I got -1.29 IQ points for a C-section (p = 0.002). With a control for SES in the form of education years and the SEI score, that went to -0.92 (p = 0.018). In the mother FE that just controls for sex and birth order, the result was +1.53 (p = 0.12).
In an OLS with demographics, SES, birth weight, gestational age, and Apgar total, I get -0.88 (p = 0.030). Mother FE with birth weight is +1.51 (p = 0.12) and with added gestational age and Apgar total, it's +0.77 (p = 0.47).
So, I'd say, not much evidence for C-section benefits here.
Alas!
Incidentally, I also checked out whether head circumference predicted being a C-section birth in this cohort, and the answer is no! Head circumference at birth was 33.66 cm for vaginal births and 33.60 for C-sections and there seems to be an elevated risk of C-section for both extremely small- and extremely large-headed babies. Within families with discordant births, there's no gap either, and power is too low to detect if there's a difference between extremes.
This is a good cohort to test this in because, in the '60s, C-sections were driven by obstetric emergencies like malpresentation, fetal distress, prior C-section, etc., rather than size measures per se.
Slightly off topic, but what was your process of actually finding, scanning, and digitizing the microfiche? I'm sure this could be done with other datasets, very cool work.
The people who scanned it in did all the physical work of moving all the microfiche into the scanners and uploading it. I took what they uploaded in various formats, aligned it, OCR'd it, and cleaned it up.