I have always been curious about season of birth can affect a person later in life. The prospect that someone may have a disposition to be more successful or healthy as an adult based off when they were born is a fascinating idea to me. If something like this could be determined on the grounds of scientific evidence, then would a rational person plan a pregnancy around the most advantageous time of year in order to ensure success and or health for their child? It has always been my understanding that birth time of year was related most closely with age in school when it came to success later in life. Those who were older than their classmates would receive better grades, have an advantage in athletics, and be better prepared later in life. In America, for most schools, this would be fall birthdays as those students are usually the oldest in their class. Either way, this was an understanding I had with no scientific backing, but rather just something I thought to be true. In this entry I will be further examining the idea that season of birth could have an impact on someone later in life
A study recently came out in Heliyon that tracked birth month versus many other variables. This study, published October 12th, included 450,000 participants in the United Kingdom, and the results were very conclusive. What the study found was that children born in the summer months (June, July, and August) weighed more at birth, reached puberty later (for females), and had a taller adult height on average then those born in the winter. Not only this, the study found those born in the summer were more likely to continue education past age 16. In terms of analyzing this study, it can be a bit difficult at times. For example, they state that one mechanism by which babies born in the summer live to be taller and healthier is because of sunlight exposure during pregnancy. If a baby is born in the summer however, would that not mean that the mother saw less sun exposure during the winter months? Another part of this study that leaves me scratching my head are the four variables that are reported on. They handed out questionnaires to a very large sample of people, and took the four most conclusive correlations that lined up with their hypothesis. In this regard, the study appeared to suffer from the Texas sharpshooter problem, as they were just painting targets around their guesses and making them look like bull’s’ eyes. The study also states that the results are most likely affected by a third variable. The study reads:
“Month of birth is highly likely to be randomised to confounding factors, and resulting associations are not subject to reverse causality. These associations therefore represent causal, rather than correlative, relationships with effect sizes similar to genetic determinants identified for these traits.”
Those are topics frequently mentioned in class and is important to keep in mind when evaluating this study. Overall, the study is well conducted and they did manage to find a correlation, but just like any study that has a new finding, there has to be more studies done in order to determine that the results were not due to chance
One reason this study is more convincing is due to the fact that it is consistent with the findings of other studies. Many studies have found relationships between health and season of birth. For example this study that found summer babies are less likely to have schizophrenia. This study found summer babies are less likely to have bipolar disorder. This study showed summer babies are less likely to get melanoma. There are tons of studies like these, and what almost all of them find is that babies born in the summer are less likely to have health issues later in life. It may seem improbable at first, but with all of these studies pointing to summer babies being healthier, the idea is is worth some thought at the very least. So based off the studies we have seen, summer babies will be healthier, taller, and will stay in school longer. These are all traits we assign to someone who is perceived to be successful.
While there are many studies showing that summer babies are better off, not everyone is in agreement. There are a few studies out there that claim summer babies are actually at a disadvantage. This study in particular comes to the conclusion that those born in the fall and winter are more likely to score higher on tests than those born in the summer. This is not the only study to come to this conclusion either. There are many studies that reiterate similar messages, kids who are older then their classmates tend to do much better in school. This creates a very interesting problem, there are lots of studies saying kids born in fall do better in school, but now we have studies that say kids born in the summer stay in school longer. While at first it may seem like the studies directly conflict each other, it appears that they are actually measuring different things. The first school of thought, upon which many studies were done in the 2006 through 2011 time frame, state that kids born in the fall tend to excel as kids. The second school of thought, which many studies are being published on now, state that kids born in the fall excel as adults. For example one group of studies look at test scores as a kid while the other look at adult height. These are two very different variable to test for.
In conclusion, there is not sufficient evidence to suggest that children born in the summer months are more successful. Even if summer babies grow up to be taller and have less health issues, fall babies still might do better in school. Judging which is more important for success later in life is very hard to do, as for one person testing well and getting good grades might be the most important, but for others being taller and having a smaller chance of having health issues may be more important. Due to how subjective the data currently is, it is impossible to say that summer babies do in fact have an advantage.