Are today’s babies getting bigger? In order to answer this question, Dr. Emily Oken looks closely at the secular trends in fetal growth around the world. In developed countries, there has been a tendency towards increasing birth weight, particularly in the last half of the 20th century. The US, for example, recorded an approximately 60 gram increase in birth weight amongst term singleton babies during this period. But upon closer scrutiny, Oken reveals that this observation has reversed itself in the last ten years: babies born after the year 2000 had lower birth weights compared to those born in the 1970s-1990s.
National surveillance data around the world reflected the same peculiar inversion in birth weight. Why are babies suddenly getting smaller? The answer lies in how we estimate gestational age. Using the techniques of last menstrual period (LMP) versus clinical evaluation, the estimated gestational age of babies differs slightly, thereby affecting the estimates of birth weight versus gestational term. Oken ends her talk with the heaviest recorded baby, weighing in at a staggering 10.8 kg.