Dating pregnancy from conception calculator
Calculate your likely conception date, once you have an estimate of your baby's gestational age.Since pregnancy dating usually counts the length of time since the start of the last menstrual period, conception takes place when you are considered 2 weeks pregnant.On average, it takes 13.6 days after conception for an test to turn positive, according to a study by the charting website Fertility On the date of your first pregnancy test -- you should at minimum -- be about 2 weeks past conception.
Abdominal ultrasounds during this time period may underestimate a baby's age by 1.6 days.
However, this only provides a rough estimate of gestation, since a variety of factors -- including fibroids, multiple babies, the amount of amniotic fluid and the baby's position -- can all influence the measurement.
By 28 to 30 weeks of pregnancy, measuring fundal height with tape measure becomes too inaccurate.
Based in southern Idaho, Michelle Johnson started writing in 1991.
Her work has been published in the science fiction and fantasy journal, "Extrapolation." Johnson holds a Bachelor of Arts in creative writing and a Master of Arts in fantasy literature, both from Hofstra University in New York.