Fun fact: Your baby lets you know when you are pregnant
Drug store pregnancy tests work because they test the level of HCG in your urine. HCG or human chorionic gonadotropin is a hormone produced by the embryo following implantation. About 5-6 days after pregnancy a fertilized embryo has multiplied into a multicellular organism called a blastocyst. If this blastocyst successfully implants into the endometrium*, the embryo begins to produce HCG.
HCG levels grow exponentially
Initially, HCG levels are miniscule, but double every 48-72 hours. As a result by about 2 weeks after implantation blood HCG levels can be used to confirm pregnancy. By 4 weeks, HCG levels in urine are high enough to be picked up by a home pregnancy test. The pregnancy test works through a fascinating mechanism of antibody binding; the positive indicator on the pregnancy test is literally drawn on a microscopic level, as shown in this 3D medical animation.
How old is your baby?
Unfortunately, since HCG levels grow exponentially, the range of HCG levels for any given week of pregnancy is very large. (see also: Guideline To HCG Levels during Pregnancy) Therefore, it is impossible to back calculate the exact day of implantation or conception. In fact, when physicians say that you are in your 6th week, they mean it has been 6 weeks since your LMP – your last menstrual period. In reality, the fetus is normally 1-3 weeks younger than 6 weeks since conception would normally happen between 7-22 days into your cycle. The only true way to determine the date of conception is to go through an IVF cycle. In IVF – or in-vitro fertilization, the egg is removed from the uterus and fertilized in a petri dish (often made of glass; vitro = glass in Latin). The fertilized egg is grown in a lab into a 6 or 8 celled embryo or into a blastocyst, before insertion back into the uterus. As such the exact age of the baby is known.
However, since all of our scientific understanding on how pregnancies progress is based on the concept of LMP, even an IVF babies age will be described as a number of weeks from LMP even though the actual age of the fetus, to the day, is known. Poor baby!
* The uterine lining, which, most likely, has been building in anticipation of nurturing a pregnancy
Gynecology
Animation in women’s health and gynecology is the therapeutic area where all of our technical and experiential strengths align. Ask us to quote for a project, and then tell us you are “going with someone else” and you’ll have us walking around in circles, Read More..
