Definition: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Input: What difference does birth order make? It has long been the source of debate in many families, and now new research suggests being the oldest may have an impact on women's weight. 
  
 When compared to their younger sisters, firstborn women are slightly more likely to be overweight or obese as adults, according to a new study published in the Journal of Epidemiology & Community Health. 
  
 In the observational study, researchers from New Zealand analyzed data from the Swedish Birth Register, which contains information dating back to the first newborn checkup on 99 percent of all births in Sweden since 1973. 
  
 The authors focused on the time period between 1991 and 2009. They looked at women who were at least 18 at the time of their first pregnancy and who had been born to a mother at least 18 years old at the time. In all, they analyzed data on 13,406 pairs of sisters - a total of just under 29,000 women. 
  
 The women's weight and height were measured and information on current health, lifestyle and family history were collected. 
  
 The analysis showed that at birth, firstborn girls were slightly lighter than their second-born sisters, but as adults, the story was a bit different. When the women grew up and were expecting children themselves, during the first three months of pregnancy, firstborns had a 2.4 percent higher body mass index (BMI) than their second-born sisters. They were also more likely to be overweight or obese. 
  
 This is the largest study of its kind done in women. The findings are in line with similar studies done in men, including one study by the same research team that found firstborn men are at an increased risk of diabetes and high blood pressure. 
  
 The researchers acknowledge that no definitive conclusions can be drawn from this study, and the reasons why firstborn children may be at a greater risk for certain health problems is unclear. 
  
 Lead study author Professor Wayne Cutfield from the Liggins Institute at the University of Auckland hypothesizes that there may be a change in the blood supply to the placenta between first and later pregnancies, with the vessels more narrow in the first pregnancy. This in turn could reduce the nutrient supply, he says, reprogramming the regulation of fat and glucose, so that in later life the individual is at risk of storing more fat and having insulin that works less effectively. 
  
 Dr. Maria Peña, Director of the Center for Weight Management at Lenox Hill Hospital in New York City, says although this is one plausible theory, environmental factors are most likely also at play. 
  
 "In many cultures, moms are more meticulous with their firstborns," she told CBS News. "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." 
  
 Such eating habits could stick with the individuals throughout their lives, she said. "People that develop obesity later on in life forget to listen to the signal in their brain that tells them to stop eating. Early on in life, some kids are taught to override that signal. If a parent tells a child to keep eating even when they're not hungry, then that's a habit they learn." 
  
 Peña, who was not involved in the birth order study, said future research in this area should look at more diverse populations, including women of different races, education levels and socioeconomic backgrounds. ||||| Abstract 
  
 Background A number of large studies have shown phenotypic differences between first-borns and later-borns among adult men. In this study, we aimed to assess whether birth order was associated with height and BMI in a large cohort of Swedish women. 
  
 Methods Information was obtained from antenatal clinic records from the Swedish National Birth Register over 20 years (1991–2009). Maternal anthropometric data early in pregnancy (at approximately 10–12 weeks of gestation) were analysed on 13 406 pairs of sisters who were either first-born or second-born (n=26 812). 
  
 Results Early in pregnancy, first-born women were of BMI that was 0.57 kg/m2 (2.4%) greater than their second-born sisters (p<0.0001). In addition, first-borns had greater odds of being overweight (OR 1.29; p<0.0001) or obese (OR 1.40; p<0.0001) than second-borns. First-borns were also negligibly taller (+1.2 mm) than their second-born sisters. Of note, there was a considerable increase in BMI over the 18-year period covered by this study, with an increment of 0.11 kg/m2 per year (p<0.0001). ||||| The idea that first-borns hold an esteemed place in the universe has been popularized for centuries. In Greek mythology, the first-born immortals were thought to control the elements -- the sky, water, light -- and in many other cultures eldest sons are treated with special privileges in everything from schooling to inheritance. 
  
 In recent years, researchers have purported to find that first-borns tend to be high achievers and more sociable. While some of this research has been found to be as reliable as astrology (that is, not at all), scientists have continued to study the extent to which your birth order matters for your life and health. 
  
 The most recent research has to do with weight, and, in this regard, it turns out that being born first may not be so good after all. 
  
 In a study published in the Journal of Epidemiology & Community Health and one of the largest of its kind, researchers analyzed data from 13,406 pairs of sisters in Sweden. 
  
 [Scientists have discovered whether being a first, second or third child makes a difference] 
  
 At birth, those born first were more likely to be slightly lighter than their sisters according to the analysis. But something changed as they grew up. As adults, first-borns were significantly more likely to have higher BMI and be overweight or obese. 
  
 Specifically, first-borns were 29 percent more likely to be overweight and 40 percent more likely to be obese than their second-born sisters. 
  
 The findings are consistent with previous research that showed that birth order may be inversely associated with BMI. A New Zealand study on 50 middle-aged men who are overweight, for instance, found that first-borns had a BMI that is 1.6 kg per square meters greater than second-borns. 
  
 Wayne Cutfield, a researcher at the Liggins Institute at the University of Auckland and the lead author of the women's study, wrote in the study that the triggers and mechanisms for the findings are unknown. But, according to CBS, he hypothesized that it may have to do with what happened to the women in utero. 
  
 He explained that there may be a shift in the blood supply to the placenta that occurs between the first and later pregnancies. In the first pregnancy, the blood vessels may be narrower, which reduces the nutrient supply and may make them store more fat. 
  
 "[O]urs was not only the largest study of birth order effects on women, but was also the only one focusing specifically on sibling pairs, to largely account for genetic factors and the early life environment," Cutfield and his co-investigators wrote. 
  
 The study is part of mounting evidence that shows that first-borns may be at an increased risk of adverse health outcomes, including diabetes type 1 and hypertension later in lives. 
  
 Read more: 
  
 It turns out parenthood is worse than divorce, unemployment — even the death of a partner 
  
 Why the healthy school lunch program is in trouble. Before/after photos of what students ate. 
  
 Study: Autism, creativity and divergent thinking may go hand in hand |||||
Output:
Attention, big sisters: First-born women are more likely to be overweight or obese than their younger sisters, a new study suggests. The Washington Post reports that researchers at the University of Auckland looked at 13,406 pairs of Swedish sisters and found the older sibling was 29% more likely to be overweight and 40% more likely to be obese. First-born sisters also had a BMI 2.4% higher than their sisters in the study, which looked at the women during their own pregnancies, according to CBS News. Interestingly, the Post points out first-born women tended to be lighter at birth than their younger sisters. This was the largest study ever on the effects of birth order and also the first study to look at pairs of siblings to account for genetic and home-life factors. The results from the study fit with those from earlier studies that showed first-born men have a higher BMI at middle age and are more likely to suffer from diabetes and high blood pressure. Study author Wayne Cutfield tells CBS first-borns may be fatter because they received less nutrients through the placenta than their siblings, preprogramming their body to store more fat after they're born. In subsequent births, babies get more nutrients because mom's blood vessels are wider. Another researcher has a simpler explanation: First-borns tend to get overfed. The study, published in the Journal of Epidemiology & Community Health, also claims this may be why worldwide average BMIs are on the rise; increasingly smaller family sizes mean more first-borns skewing the average. (But at least first-borns have higher IQs, right?)