GROWTH AND DEVELOPMENT OF HUMAN FETUS PRIOR TO TWENTIETH WEEK OF GESTATION

The rate of growth of the human fetus from the fifth to the twentieth week has been ascertained by sonographic mensuration. Three separate structures have been measured in 103 gravidas whose last menstrual periods were known precisely. Uterine size was measured throughout the period of study. The size of the gestational sac was ascertained from the fifth to the tenth week of gestation when it begins to disappear, and the biparietal diameter of the fetal head from the time of appearance (twelfth week) to the twentieth week. Regression lines with estimates of error correlating the several measurements with the length of pregnancy have been constructed. These lines demonstrate a linear rate of growth of the various structures during early pregnancy. Significant deviations from these growth rates appear to indicate abnormal development. © 1969.