What is miscarriage?

By Professor Charles Kingsland, Consultant Gynaecologist & Specialist in Reproductive Medicine


Human beings, generally speaking are not good at reproducing. We have 12 or 13 opportunities per year to get pregnant, every time we ovulate in fact. When we do get pregnant, our pregnancies are exceedingly long, about 270 days, which is the third longest pregnancy of any animal. Which animals have longer pregnancies I hear you ask? The giraffe is pregnant for up to 15 months, the sperm whale up to 17 months and the prize for the longest pregnancy? The elephant, lasting 20-22 months – almost two years!

Many of our pregnancies don’t last very long. They end prematurely, a so called miscarriage. Humans miscarry lots of times and usually for a very good reason. We have some very strange ideas about miscarriage, which are still prevalent in my practice today. I think it would be worthwhile spending a little time on this desperately misunderstood and underestimated event at this point.

Some studies have suggested up to 50% of pregnancies that start out in humans end in miscarriage. When we miscarry, we often talk about ‘losing’ the baby, giving the impression that within the mother’s womb there is a tiny well-formed baby, hanging on by his finger-tips, screeching to his would be mummy to not let him fall out. This is not only factually incorrect, but in my opinion, only serves to heap further guilt on the female implying the loss of this otherwise normally formed human is solely the responsibility of the flawed mother.

Well nothing could be further from the truth. The fact is that many eggs which fertilise, do so abnormally and the older the woman gets, the more those abnormalities occur to the stage when, at the age of 40, as many as 75% of all embryos created are chromosomally abnormal.

Therefore, in the vast majority of cases, the female uterus is doing exactly what it’s supposed to do by rejecting the abnormal baby. Uteri or ‘wombs’ as we like to call them in the trade, are very clever animals indeed. They do what they are told to do by hormonal messengers.

When an embryo is formed, it sends messages to the uterus to say I’m on my way and get ready to grab me. These messages pass down to the womb as the embryo is wafted on a tide of tiny little hairs in the fallopian tube, which beat synchronously, thus propelling the embryo on its way to implantation. The embryo divides as it goes; two cells to four to eight to 16, doubling in cell number every 24 hours or so. It then enters the vast space of the uterine cavern, at around 64 cells in size, where upon more often than not it sticks into the pre-prepared thick juicy lining of the womb, the endometrium.

After that, the womb gets to work, examining the embryo for normality and feeding it as it goes. Then the clever bit happens. If the embryo is normal, the chances are it will grow into a healthy baby. If abnormal, the uterus will reject it, with the result that the embryo will be expelled and will drop out. If the uterus is unsure, the abnormal baby may grow for a number of weeks until it is rejected, with the result that the uterus may bleed and cause pain as it contracts to expel the non-viable products of conception.

It’s interesting to note at this point that fertile women often miscarry pregnancies they know little about. For example, a perfectly fertile woman, with regular periods may at some time experience a late or somewhat heavy period. She may think momentarily that it was a strange occurrence and carry on normally. Well that could well have been a miscarriage. They are that common.

There is little that doctors can do to save a doomed early pregnancy. A pregnancy of over three months when the baby is well formed is completely different. That’s why many of the more pragmatic doctors will do nothing and adopt a wait and see policy, with psychological support, obviously. They may tell you to go home, put your feet up and rest. If the baby is normal, there is an overwhelming chance that it will survive. If not, the rejection will be complete and the contents of the womb will be expelled, in whole most of the time or in part occasionally, in which case it may be necessary for doctors to intervene and help the pregnancy to evacuate so that everything can start again.

Hence bleeding in early pregnancy can happen and can be normal, whilst bleeding and pain is never a good sign. Resting can help and it certainly makes us all feel better, but it won’t change the outcome.

Healthy babies, don’t forget, are little parasites. They will cling on for grim death and will survive at all costs. You can be run over by a bus in early pregnancy and a normal pregnancy will usually survive.

I remember, in the early 80s, a number of soap operas from the United States; I’m thinking of Dallas and Dynasty in particular, usually had a weekly dose of some glamorous pregnant family member falling down the spiral staircase in Southfork, on her way to the Cattlemans Annual Ball and ending up on a life support machine, just before the adverts started.

After a week of high expectation as to what happened next, the following episode would start with JR and Bobby and Jock and Miss Ellie surrounding the comatose Sue Ellen or Crystal or whatever her name was, to be told by a rather dashing brylcreemed fop in an improbably crisp white coat (where have they disappeared to in our hospitals?) that Pam will make a full recovery, normally in time for the next episode, but tragically, she has ‘lost’ the baby.

Much whaling and nashing of teeth ensues. She’s lost the baby? Oh Miss Ellie, whatever are we gonna do? Lost the baby? Where on earth could it have gone? Well, the far more likely scenario in early pregnancy is that poor old Pammy, has fractured her neck, is paralysed from the eyebrows down and will never be able to wear lipstick again, but the baby inside her is still fit and well. Why? Because the baby is a little parasite, is normal, and has been cushioned from harm because it is growing in a big muscular watery box, as good as any metal safe.

Later in pregnancy, usually from the 12th week onwards, the baby is not so safe from harm, because the womb has grown outside of the bony pelvis and is little more exposed to the elements. Even then, however, there is good load of fluid surrounding it. Have you ever tried to spear a gold fish with a wooden toothpick in a gold fish bowl? Try it. It’s difficult. In any case from the 12th week onwards, the baby’s bits are all fully formed and all it has to do then is to grow. An ultrasound scan can be helpful in assessing whether a pregnancy is viable or not.

From about 35 days after conception, it is possible to see a baby’s heartbeat, which is usually a good indicator as to whether the baby will live or not, at that stage. If you see a heartbeat at this stage, there’s a 90% chance you will end up with a healthy baby. As I mentioned before, the uterus is a very clever beast indeed; 97% of all miscarriages are chromosomally abnormal. The commonest chromosomal abnormality is Downs syndrome and did you know for every hundred Downs syndrome babies that are conceived, only one is ever born? Most other abnormalities are lethal long before birth.

Now think of this; some doctors would argue that uteri miscarrying babies just get the messages wrong. So, instead of not implanting the embryo and just letting it pass through untouched, as many wombs will do, they hedge their bets and implant the embryo just to have look.

It is rare that a uterus gets it wrong. Occasionally, however, a womb may get messages completely wrong and will continue to miscarry normal embryos, so called recurrent miscarriage, but this is a rare condition and specialists are prone to over diagnose this problem.

Finally, whilst we are on the subject of early miscarriage, beware the specialist bringing gifts of pill and potions designed to prevent the loss of the early pregnancy. There is little evidence that anything works, except one very, very important thing, and that is, wait for it, nature itself.

A smart (and often rather costly) doctor will offer you some reassuringly expensive medication, that although not harmful and in theory, beneficial, in reality is of absolutely no use whatsoever. After you recover, you will then be led to think of that gynaecologist as a hero, tell your friends and maybe even resort to Twitter and Facebook to extol the virtues of this miracle worker.

The reality is, however, far less romantic in that nature took its course. You were going to recover, despite the medication you were prescribed and not because of it. Still, if you are a medic trying to make a name for yourself, it may be worth a shot and if the medication isn’t harmful, so what? Mmm... I’m not so sure. One thing is for sure; having a miscarriage can be extremely unpleasant and distressing for all concerned. The woman has lost her baby irrespective of its age or gestation. The uterus has been emptied prematurely. All need to grieve and grieve properly. It is inappropriate to treat the loss of any pregnancy lightly, particularly one where no one has seen a baby. The grief endured over a baby you have never seen is profound and must be managed carefully and considerately.

It is all too easy to say, in an effort to be helpful to “Come on and snap out of it” or “It’s not the end of the world” or “You can try again.” But to that would be mother and particularly to the lost baby, at this moment in time it is, in fact, the end of the world.

Professor Charles Kingsland