Early Days: The Biochemical Phase Of Pregnancy
If a woman has a blood pregnancy test and is not pregnant, the test will be negative because the pregnancy hormone (beta hCG) is not present. During pregnancy, hCG circulates through the bloodstream. Though initially, the levels of this hormone are relatively low, in a healthy pregnancy, the hCG doubles approximately every 72 hours.
During this very early stage of pregnancy not only does the woman not look pregnant, but the pregnancy cannot yet be detected with an ultrasound scan. This stage is called the biochemical phase because the pregnancy can only be detected using a biochemical blood test. Eventually, the levels of beta hCG will rise, and evidence of the pregnancy will be detectable with an ultrasound scan. Meanwhile, the biochemical phase is the time from conception or implantation to the time the baby can be seen using ultrasound.
Down the road: the clinical phase of pregnancy
A clinical pregnancy is one which has been confirmed by high levels of the pregnancy hormone, and an ultrasound scan has been used to detect a fetal heartbeat. If a pregnancy ends before it has been confirmed by ultrasound, this is known as a chemical pregnancy.
There are four signs of clinical pregnancy. The first is a visualization of the gestational sac; this is the fluid-filled sac which will later become the amniotic sac. The second is a visualization of the yolk sac; this provides nourishment to the embryo. The third is a visualization of the fetal pole; this is the thick area attached to the yolk sac. The fourth is the fetal heartbeat.
Delayed signs of clinical pregnancy
If a woman has had an ultrasound scan and it has not revealed the sings of clinical pregnancy this may be for one of several reasons. Sometimes the position of the uterus or the location where the embryo has implanted can cause a delay in signs of clinical pregnancy.
Understanding the difference
When trying to conceive, the only way to be certain of pregnancy is to consult a healthcare professional. While at home pregnancy tests can be helpful, many tests can show a false negative even though the woman may be pregnant.
