Bad news, big sisters: A new study finds that firstborn girls are more likely to be overweight or obese than their second-born sisters.
The findings are based on data collected from more than 13,400 pairs of sisters born in Sweden.
According to the study, older sisters are 29% more likely to be overweight and 40% more likely to be obese than their next-younger sister. Firstborn girls are also, on average, a little taller than their sisters as adults.
The results were published this week in the Journal of Epidemiology & Community Health.
The researchers say the weight discrepancy does not begin at birth.