Thus, the evidence seems to be shifting back in favor of our common intuition that our position in our family somehow affects who we become. The details, however, remain vague. The Norwegian study shows a slight effect on intelligence. The relationship study shows that oldest, middle, youngest and only children differ in some way yet gives no indication as to how. Moreover, although these effects are reasonably sized by the standards of research, they are small enough that it would not make any sense to organize college admissions or dating pools around birth order, much less NASA applicants.
In October 2013 the largest study of this kind was published in the American Journal of Obstetrics and Gynecology and included data on more than 13 million births in the United States, assessing deliveries by physicians and midwives in and out of the hospital from 2007 to 2010. The study indicated that babies born at home are roughly 10 times as likely to have an Apgar score of 0 after 5 minutes and almost four times as likely to have neonatal seizures or serious neurological dysfunction when compared to babies born in hospitals. The study findings showed that the risk of Apgar scores of 0 is even greater in first-born babies—14 times the risk of hospital births. The study results were confirmed by analyzing birth certificate files from the . Centers for Disease Control and Prevention (CDC) and the National Center for Health Statistics . Given the study's findings, Dr. Amos Grunebaum, professor of clinical obstetrics and gynecology at Weill Cornell Medical College and lead author of the study, stated that the magnitude of risk associated with home delivery is so alarming that necessitates the need for the parents-to-be to know the risk factors. Another author, Dr. Frank Chervenak, added that the study underplayed the risks of home births, as the data used counted home births where the mother was transferred to a hospital during labor as a hospital birth.