I believe there is not a single cause, but multiple. It does occur naturally sometimes..

What is miscarriages? Is it like abortus?

Often, miscarriages are because of some diseases. Can be thought as the nature’s protection for having healthy individuals. But this is not always the case. The exact reason can not be found. It is natural. If you ask about "abortion", it is artificial.

For exact definition, you can say "Loss of pregnancy".

I have to tell you that it is different between "abortus" and "abortion" 😉

You’d be surprised how common miscarriages are. My sister had one and she is a perfectly healthy person. I’ve grown up around nurses and apparantly alot of women have miscarriages when they are young, especially on their first try. The menstrual cycle is different in every woman and I wonder if an irregular cycle plays a role in miscarriages.

The level of estradiol really contributes on miscarriage 🙂

I know the difference. I think I couldn’t explain it clearly. I mean, if you are talking about ( I was answering the authors’s question) loss of pregnancy with your decision,artificially, that is abortion.
I used the word correctly, not referring to miscarriages.

I was talking about the diseases in the baby, not the mother. Plus this is one of the reasons, not the only reason.

Ok, understood 🙂

Most miscarrages occur because the baby isnt viable and couldnt survive because of events which happen during fertilisation or because its getetic code is flawed. Most miscarrages also occur during the first few days of pregnancy even before the mother knows shes pregnant-which is probably a blessing.

A miscarriage is pregnancy lost before 20 weeks. It could be caused by thyriod disease, choromosomal abnormalities, diabetes.

I used to work in a laboratory that dealt with trying to determine why spontaneus abortions (miscarriages) happened.

Basically, the ob/gyn would send us an entire fetus or a part of it. I’ve probably looked at 3,000 and after a while I got to the point that I can look at fetal structure (morphology, tissue and chorionic villi) and tell if something was wrong!

When we performed further analysis …. 99.99999% of the aborted fetuses that looked abnormal were in fact GENETICALLY abnormal (too many/few chromosomes, loss/Gain of DNA fragments, gain of entire chromosomes)

And approx. 40% of those that appeared normal indeed had non-viable genetic changes.( too many/few chromosomes, loss/Gain of DNA fragments, gain of entire chromosomes, large and small translocation, single gene loss/gain)

Of course there clearly is a subset of diseases that are difficult to diagnose in a clinical lab … and because of the resolution of our clincal studies it is very possible that were were not able to accurately diagnose a genetic problem (a lethal one).

From my personal experience … I strongly believe that "misscarriages" are nature’s way of "getting-rid" of something that’s "sickly" or "non-viable" …

(OF COURSE!!! there are other reasons why misscarriages DO happen … but the VAST majority is due to genetic incompatibilitly)

the rule of thumb??? If a woman has more than 3 miscarriages there is a SERIOUS posibility that genetics underly the problem … therefore, wife and husband should speak to a geneticist … who will be able to determine if that’s the problem and determine a next-step towards a solution. (ie. in-vitro fertilization.. ). This situation is generally NOT completely hopeless… cuz the technolgy is availiable to help .. (i’ve worked veryy closely with a leading doctor in New York City and seen HUNDREDS of sucess stories!!!)

kewl beans!
– KIM

What you say is very interesting, KIM, and such work is very worthwhile, as it can lead to the couple achieving success eventually.

However, a laboratory such as the one you worked in would only have been sent those fetuses the clinician thought may have a genetic abnormality, based either on gross morphology/pathology, or, (as you rightly mention), the woman’s obstetric history, in which 3 or more pregnancies ended this way at a particular stage of gestation.

Therefore, although 99.9% of the fetuses you examined could well have had a major genetic flaw, that would not necessarily mean that this would be the figure and cause underlying all miscarriages.

A lot depends on the point of gestation reached, but many causes abound, ranging from viruses, rhesus incompatibility, (yes, even today!), trauma, foreign body, placental insufficiency, cervical incompetence, to name but a few.

As atypical10 has already pointed out, a miscarriage is a pregnancy that ends before 20 weeks. Expanding from that, a miscarriage can also be referred to as spontaneous abortion.

There are different categories of miscarriages: early which is before 8 weeks of gestation and late which occurs between 12 and 20. There are also different types of miscarriages including threatened, inevitable, incomplete, complete and missed.

The causes for early miscarriage can vary from endocrine imblances, infections, systemic disorders or genetic factors. Some causes for late miscarriage can be the age of the mother, infection, premature dilation of the cervix, poor nutrition, and drug use. However, there are some miscarriages that happen for unknown reasons.

Here is quote from my mol. genetics text. Maybe it is relevant?

I think you are right, in that the term ‘spontaneous abortion’ means something quite distinct, so these types of miscarriage would have a very high genetic loading as a cause.

I don’t think we can use this term, i.e. spontaneous abortion), as synonymous with miscarriage per se, though, and it is within this classification that the genetic causes may not be quite so high. (At least in our present stage of knowledge, perhaps).

Does the book definitely say that 90% of all chromosomal anomalies are terminated prior to birth as result of spontaneous abortion?

I am just curious. Do they mean major anomalies, or are they perhaps including therapeutic abortions in the figure? It seems a strange way to put it, if not, i.e. ‘prior to birth..’.

Also, if the authors of the book state that only 30% of all spontaneously aborted fetuses demonstrate some form of chromosomal anomaly, I don’t understand how the figure jumps to 90% of all fetuses undergoing spontaneous abortion prior to birth.

There is quite a lot of such pregnancies that do, sadly, end by means of a therapeutic abortion, so I do not think that 90% of all chromosomal anomalies can end purely in spontaneous abortion.

Then, there are the babies born with chromosomal anomalies. It depends on what is meant by this term, but many conditions have a chromosomal ‘anomaly’ at their root.

Maybe I am missing something, but, at first sight, these figures seem wrong to me.

Yes, as far as miscarriages vs spontaneous abortions, I am not sure. Maybe definition subjective?

Abortions listed are not by choice of parent of physician is that is what therapeutic abortion mean. Just spontaneous.

For percentages, I do not see conflict that you say. It says 30% of original 15%-20% demonstrate chromosome anomaly. So now we have percentage of 6% assuming original is 20%. So now we can say 6% of spontaneous abortion due to chromosomal anomaly.

For 90% is taken as different ratio. This ratio out of all babies that have chomosomal anomalies and are spontaneous aborted. If 100 babies are conceived with chomosome anomaly, only 10 will survive is way to look at it.

And chomosome anomaly refer to any deletion, inversion, aneuploidy, duplication, translocation, fragile site, etc..
Anyway, hope explanation helps.

Hi,

It could well be that I am missing something, because figures are not my strong point!

I think that there is a medical definition of spontaneous abortion, and of miscarriage, (there is certainly a legal one), but I would have to check my textbooks. I don’t think these definitions are subjective.

I could also be wrong about this, but I do not think that, out of every 100 fetuses conceived with a chromosomal anomaly, only 10 will survive, (by virtue of nature’s input alone). This may be true of very serious anomalies that are largely incompatible with life, but not of all of them.