With various current events in the media lately, there are a lot of debates flaring up again over embryo rights and the definition of when life begins. And after reading a study a reader of this site sent to me the other day, I realized that these issues have a connection to the definition of a miscarriage. Usually when people are debating abortion, they argue over questions such as when life truly begins, and the viewpoints can put the start of life anywhere from fertilization to the moment of birth. No one really agrees, thus people argue over whether an early pregnancy involves a baby or a "potential baby," etc.
But putting aside the question over the start of life, there's kind of a similar conundrum in the question over when a pregnancy truly begins -- and the difference of opinion could lead to misunderstandings over what constitutes a miscarriage. The traditional 40-week pregnancy calendar confusingly starts counting weeks of pregnancy at the start of the menstrual cycle, which is two weeks before the sperm even meets the egg (so you're "two weeks pregnant" already when you conceive). Then there's another week where the fertilized egg is floating through the reproductive tract before it implants in the uterus, which is when your hCG levels start to rise. And the implantation process sometimes goes awry, perhaps causing a slight rise in hCG levels, but then the woman's menstrual period comes right on schedule or a few days late (a chemical pregnancy).
So one wonders: when does the pregnancy actually begin? Is it from the time of fertilization? Implantation? Or from the time that the pregnancy becomes "clinical" as opposed to "chemical," even though the latter does involve a fertilized egg and rise in hCG?
I've noticed that people tend to have different opinions on this and it can have some ramifications for the definition of a miscarriage. Despite counting weeks of pregnancy from the start of the menstrual cycle, most doctors seem to define pregnancy from the point of implantation (the point at which you can detect hCG), and thus to them, anything that interferes with implantation is merely preventing pregnancy rather than causing a miscarriage. But I've noticed that a lot of moms seem to think otherwise, and many will consider any failed implantation (even a failed IVF cycle) to be a miscarriage.
And thus you end up with disagreements on numerous questions, such as whether birth control pills cause miscarriages. Researchers will tell you they don't, because there's no real evidence that they will disturb an established pregnancy or increase the risk of miscarriage in a future established pregnancy. But it's also commonly believed that birth control pills partly work by making the uterus inhospitable to a fertilized egg. Some people might say that meant they cause miscarriages, but it depends on whom you ask.
What do you think? When is a pregnancy truly a pregnancy? I'd be interested to hear your opinions.