Scientists are adjusting the previous gestation period for the average human pregnancy. Before, it was thought to be 40 weeks or so, but now researchers say the average gestation is between 35 and 40.5 weeks of pregnancy.
Until now, scientists pegged a pregnancy as full gestation between 38 and 40 weeks from conception.
The study from the journal Human Reproduction looked at of 125 women and found that on average they gave birth at 38 weeks two days – just two days beyond the normal “due date” calculation used in this country.
The findings are interesting when juxtaposed with previous findings that less than 5% of women give birth on their actual due dates.
Dr Anne Marie Jukic, a postdoctoral fellow from the National Institute of Environmental Health Sciences, from Durham, USA, researchers were “surprised” by the amount of variation in the length of pregnancies, the UK Telegraph reported.
The reason for the earlier births may have to do with one of three hormones the embryo secretes hCG (human chorionic gonadotropin)
Since the embryo secretes hCG, and mothers generally have little to no hCG in their urine when they are not pregnant, we used the earliest increase in hCG to indicate implantation,” Dr. Jukic told Discovery.