See the surprising trends for fall babies, winter children, and more
Can the month in which you were born determine the rest of your life? As odd as it sounds, the evidence mounts up. Every day, we pour through endless medical studies, and we repeatedly come across fascinating research that links your birth season with your health later in life. Scientists aren't sure why these connections exist, but hypothesize that some environmental factors—say, vitamin D levels or temperature fluctuations—may be responsible.
Check out the following conditions associated with certain birth months—but don't freak out if your birthday plunks you right into the "danger zone"—these studies can't prove cause and effect, and there are still a lot of uncertainties that come along with them.
Born In The Fall: Food Allergies
Kids who were born in the fall are anywhere from 30 to 90% more likely to develop allergies to milk, eggs, or peanuts than children born in any other season, a 2012 study in the journal Allergy found. One potential reason: Fall babies experience a lack of vitamin D during a crucial developmental period. This can affect their immune system and leave them susceptible to certain allergens. What's more, not enough D can decrease the barrier function of your skin during this time, possibly allowing allergens to penetrate.
Born In The Fall: Asthma
Your birthday might be something to wheeze at: A 2013 study from Taiwan found that kids who were born in the fall were 13% more likely to develop asthma than those born in the spring. The researchers think that being exposed to cold weather during your first few months of life can trigger allergic reactions that lead to asthma.
Born In The Winter: Socioeconomic Disadvantages
Winter babies are born unlucky, according to a 2009 study from the University of Notre Dame. Researchers analyzed U.S. census data and birth certificates and determined that mothers who give birth in winter are likely to be unmarried or without a high-school diploma, and suggested that wealthier women with better education can afford to time their births to more desirable seasons.
Born In The Winter: Lefties
New research from Germany found that men born between November and January were significantly more likely to be left-handed than those born during other parts of the year. You can likely credit the effect of testosterone on your developing fetus-brain. High levels of T in the womb can delay the maturation of your left brain hemisphere, making left-handedness more likely to develop later on. And longer periods of daylight—say, from May through July—spur higher secretion of this hormone. Men born in the late fall or early winter receive a high dose of testosterone after they've been cooking in the womb for about 4 months—the development period that's likely responsible for determining your dominant hand.
Born In The Spring: Non-Hodgkin's Lymphoma
A 2014 study in the International Journal of Cancer found that people who were born in the spring—March through May—were 25% more likely to develop non-Hodgkin's lymphoma through young adulthood than those born in September through November. And people born in April—to be super-specific, April 24—were at the highest risk of the white-blood-cell cancer. How come? The researchers believe this follows in line with something called the "delayed exposure hypothesis." This means that babies born in the spring months may not have been exposed to certain infections during a critical time of immune development. As a result, they may develop abnormal immune responses that might make them more susceptible to non-Hodgkin's lymphoma.
Born In The Spring: Autoimmune Diseases
Here's more evidence that spring-born babies might have some immune woes: A 2012 study in BMC Medicine found that the occurrence of autoimmune diseases including multiple sclerosis, rheumatoid arthritis, and ulcerative colitis peaked in people born in April. People who were born 6 months later in October were at the lowest risk.
Now, there's no need to panic if you were born just as the flowers started to bloom. Even though the findings were significant, the researchers say the magnitude of the effect of being born at the “wrong time” was very low. They estimate about 5% of these diseases could be prevented if the risk factor responsible for the seasonal spike was fixed. The researchers aren't sure exactly what that is, but they think it might be related to low levels of vitamin D during the third trimester of pregnancy. This can hamper the developing immune system, possibly increasing the risk of these diseases.
Born In The Spring: Melanoma
A new study in the International Journal of Epidemiology found that people born in the spring were 21% more likely to develop melanoma through their 30s than those born in the fall. The researchers think these babies might be exposed to higher UV exposure during their first few months of life—a critical period that might increase later susceptibility to the skin cancer. You can't turn back the clock and slather some sunscreen on your baby face, but you can protect yourself now: That means seeking shade when the sun's the hottest during midday, using sunscreen, and covering yourself with sunglasses and hats. And be especially alert if melanoma runs in your family. The study also found that people who had a sibling or parent with the skin cancer were six times and three times as likely, respectively, to develop it themselves.
Born In The Summer: Suicide
People born from late spring to summer might be at a higher risk of committing suicide than those born during other months, a 2010 Hungarian study found. July babies were nearly 14% more likely to kill themselves than children born in December, the lowest-risk month. The researchers aren't sure what's responsible for this risk, but they believe it might be due to a complex interaction between birth season and various neurotransmitters that may be involved in suicidal behavior.
Born In The Summer: Nearsightedness
Summer-born folks seem to have a lot to squint about, and it's not because of the sun. People with summer birthdays are 17% more likely to develop high levels of myopia, or nearsightedness, than those who celebrate in the winter, a study from the U.K. found. The researchers think it might have to do with seasonal differences in birth weight or other environmental features like temperature.
Born In The Summer: Mood Swings
Find yourself flying high one minute only to be inconsolable the next? You might have something called cyclothymic temperament, which is characterized by frequent and sudden swings from sad to cheerful moods. In a study recently presented at the European College of Neuropsychopharmacology, researchers found people born in the summer were more likely to have this temperament than those born in the winter.
One possible reason: When you're born can slightly alter how your neurotransmitters work. This might be due to things like available nutrients, germs or allergens in the air, or light and temperature when you're in the womb and shortly after you're born, says researcher Xenia Gonda, PhD. All of the different temperaments are expressed on a scale—dominant on one end and very mild on the other. It's when they're shown severely that they can actually be precursors to certain mood disorders, says Gonda.
Can the month in which you were born determine the rest of your life? As odd as it sounds, the evidence mounts up. Every day, we pour through endless medical studies, and we repeatedly come across fascinating research that links your birth season with your health later in life. Scientists aren't sure why these connections exist, but hypothesize that some environmental factors—say, vitamin D levels or temperature fluctuations—may be responsible.
Check out the following conditions associated with certain birth months—but don't freak out if your birthday plunks you right into the "danger zone"—these studies can't prove cause and effect, and there are still a lot of uncertainties that come along with them.
Born In The Fall: Food Allergies
Kids who were born in the fall are anywhere from 30 to 90% more likely to develop allergies to milk, eggs, or peanuts than children born in any other season, a 2012 study in the journal Allergy found. One potential reason: Fall babies experience a lack of vitamin D during a crucial developmental period. This can affect their immune system and leave them susceptible to certain allergens. What's more, not enough D can decrease the barrier function of your skin during this time, possibly allowing allergens to penetrate.
Born In The Fall: Asthma
Your birthday might be something to wheeze at: A 2013 study from Taiwan found that kids who were born in the fall were 13% more likely to develop asthma than those born in the spring. The researchers think that being exposed to cold weather during your first few months of life can trigger allergic reactions that lead to asthma.
Born In The Winter: Socioeconomic Disadvantages
Winter babies are born unlucky, according to a 2009 study from the University of Notre Dame. Researchers analyzed U.S. census data and birth certificates and determined that mothers who give birth in winter are likely to be unmarried or without a high-school diploma, and suggested that wealthier women with better education can afford to time their births to more desirable seasons.
Born In The Winter: Lefties
New research from Germany found that men born between November and January were significantly more likely to be left-handed than those born during other parts of the year. You can likely credit the effect of testosterone on your developing fetus-brain. High levels of T in the womb can delay the maturation of your left brain hemisphere, making left-handedness more likely to develop later on. And longer periods of daylight—say, from May through July—spur higher secretion of this hormone. Men born in the late fall or early winter receive a high dose of testosterone after they've been cooking in the womb for about 4 months—the development period that's likely responsible for determining your dominant hand.
Born In The Spring: Non-Hodgkin's Lymphoma
A 2014 study in the International Journal of Cancer found that people who were born in the spring—March through May—were 25% more likely to develop non-Hodgkin's lymphoma through young adulthood than those born in September through November. And people born in April—to be super-specific, April 24—were at the highest risk of the white-blood-cell cancer. How come? The researchers believe this follows in line with something called the "delayed exposure hypothesis." This means that babies born in the spring months may not have been exposed to certain infections during a critical time of immune development. As a result, they may develop abnormal immune responses that might make them more susceptible to non-Hodgkin's lymphoma.
Born In The Spring: Autoimmune Diseases
Here's more evidence that spring-born babies might have some immune woes: A 2012 study in BMC Medicine found that the occurrence of autoimmune diseases including multiple sclerosis, rheumatoid arthritis, and ulcerative colitis peaked in people born in April. People who were born 6 months later in October were at the lowest risk.
Now, there's no need to panic if you were born just as the flowers started to bloom. Even though the findings were significant, the researchers say the magnitude of the effect of being born at the “wrong time” was very low. They estimate about 5% of these diseases could be prevented if the risk factor responsible for the seasonal spike was fixed. The researchers aren't sure exactly what that is, but they think it might be related to low levels of vitamin D during the third trimester of pregnancy. This can hamper the developing immune system, possibly increasing the risk of these diseases.
Born In The Spring: Melanoma
A new study in the International Journal of Epidemiology found that people born in the spring were 21% more likely to develop melanoma through their 30s than those born in the fall. The researchers think these babies might be exposed to higher UV exposure during their first few months of life—a critical period that might increase later susceptibility to the skin cancer. You can't turn back the clock and slather some sunscreen on your baby face, but you can protect yourself now: That means seeking shade when the sun's the hottest during midday, using sunscreen, and covering yourself with sunglasses and hats. And be especially alert if melanoma runs in your family. The study also found that people who had a sibling or parent with the skin cancer were six times and three times as likely, respectively, to develop it themselves.
Born In The Summer: Suicide
People born from late spring to summer might be at a higher risk of committing suicide than those born during other months, a 2010 Hungarian study found. July babies were nearly 14% more likely to kill themselves than children born in December, the lowest-risk month. The researchers aren't sure what's responsible for this risk, but they believe it might be due to a complex interaction between birth season and various neurotransmitters that may be involved in suicidal behavior.
Born In The Summer: Nearsightedness
Summer-born folks seem to have a lot to squint about, and it's not because of the sun. People with summer birthdays are 17% more likely to develop high levels of myopia, or nearsightedness, than those who celebrate in the winter, a study from the U.K. found. The researchers think it might have to do with seasonal differences in birth weight or other environmental features like temperature.
Born In The Summer: Mood Swings
Find yourself flying high one minute only to be inconsolable the next? You might have something called cyclothymic temperament, which is characterized by frequent and sudden swings from sad to cheerful moods. In a study recently presented at the European College of Neuropsychopharmacology, researchers found people born in the summer were more likely to have this temperament than those born in the winter.
One possible reason: When you're born can slightly alter how your neurotransmitters work. This might be due to things like available nutrients, germs or allergens in the air, or light and temperature when you're in the womb and shortly after you're born, says researcher Xenia Gonda, PhD. All of the different temperaments are expressed on a scale—dominant on one end and very mild on the other. It's when they're shown severely that they can actually be precursors to certain mood disorders, says Gonda.