By definition a chemical pregnancy is a very early pregnancy loss which accounts for up to 75% of all miscarriages. Many times, a woman might have a chemical pregnancy and not even realize she had been pregnant.
Wait. How does that work?
About three weeks after your last menstrual period you begin to produce levels of the pregnancy hormone hCG that are high enough to detect on a blood or urine test. If you are not actively taking pregnancy tests you may not ever know you were pregnant to begin with and you will begin your cycle not knowing you had been pregnant.
Chemical Pregnancies are more easily tracked and detected if you are doing fertility treatments because of the early hCG testing that happens after and IUI or round of IVF.
Once the fertilized egg implants in the uterus it can somehow not complete implantation — and an ultrasound won’t be able to detect a gestational sac or placenta developing — which then results in the bleeding around a week after your regular period was due.
If you have heavy bleeding (with or without cramping) after a positive pregnancy test, call your doctor right away, as you may be experiencing a chemical pregnancy.
Why Does it Happen
When an egg and a sperm combine chromosomes it then goes on to form a zygote, which begins to grow through rapid cell division. When that happens there are occasionally mistakes that happen. Sometimes producing too many chromosomes or not enough. This can occur randomly and can happen to anyone.