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How your birth order might affect your body weight

Julia Horniacek is an independent freelance writer reporting beauty and fashion for SheKnows and, addicted to exercise, coffee and making an attempt to get outside her comfort zone.

According to new research, older siblings are more likely to be overweight than last-borns

Attention all last-born children! Apparently our favoritism starts in the womb. According to new research published in the Journal of Epidemiology & Community Health, first-born women are more likely to be overweight than their younger sisters as a result of possible changes in the blood supply to the placenta during pregnancy.

There is a 13-year age gap between me and my eldest sister. Thirteen years and four kids later, my parents had a much different approach to raising a child than they had the first time around, and don’t think for one second that my sister doesn’t love to point out the obvious differences in our upbringings. For example, what’s a curfew? While she had to clock in around midnight into her early 20s, I was told to be home at a “reasonable hour.” Better yet, what’s a punishment? Ask the sister who spent plenty of time in her room with the door closed. AKA not me. There are plenty of examples of how we were treated differently, but there was also always a difference in our bodies.

More: How your birth order affects your adult life

I remember coming home from college one weekend to stop by her Pampered Chef party (my family loves a fresh set of kitchenware), and she upheld her hostess duties by introducing me to her friends and coworkers as her little “Barbie” sister.

I have two sisters and one brother, all significantly older than me, and all of whom have struggled with weight loss. At 23 years old, I stand 5’2" tall and weigh in at about 105 pounds. While that number has certainly fluctuated over the years, I cannot recall a time in my life that I weighed more than 125 pounds, but I’ve always just assumed this was due in large part to my inability to keep still and my passion for physical activity.

More: Does birth order affect your personality?

From 1991 to 2009, New Zealand researchers analyzed 13,406 pairs of sisters. According to the study’s lead author Professor Wayne Cutfield, their results suggest that, due to narrow blood vessels during a woman’s pregnancy, nutrient supplies are reduced which can cause the individual’s body to store more fat and less effective insulin as they grow.

Elder siblings almost always get the short end of the stick when it comes to how they are treated growing up, and now we have reason to believe they also get the short end of the stick health wise. While research supports this theory, there is more to an individual’s weight than their birth order.

More: 20 Signs birth order totally matters

Director of the Center for Weight Management at Lenox Hill Hospital in New York City Dr. Maria Peña believes that outside factors affect an individual's weight gain as well. In a recent interview, Dr. Peña told CBS News, "In many cultures, moms are more meticulous with their firstborns. With the very firstborn, everyone's helping out and over-feeding the baby, making sure it's at a 'healthy weight.' But with second children, parents know what to expect and they're not so overprotective so maybe they feed them a little less."

While this brings us back to the ongoing debate of nature vs. nurture, there is no denying that ultimately, we are a product of our environment. We cannot control what order we are born into our families. We can, however, make an effort to avoid weight gain as a result of our surroundings.

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