Miscarriage - The hidden causes

Although miscarriages are often blamed on 'tired eggs' or unknown causes, the real culprits are poor diet, environmental toxins and even the drugs to help women get pregnant.

Over the last two decades, the number of couples experiencing fertility problems has risen significantly. A quarter of all couples planning a baby have trouble conceiving. One in four women miscarries. Some experience repeated miscarriages as often as 10 times.

Of the couples who seek medical help, 30 per cent are told they have 'unexplained infertility' for which the doctors can offer no treatment. If one in four pregnancies ends in early miscarriage, should we accept this high rate as 'normal'? Arthritis is very common in our society as we get older; in other cultures it is not. Does this make it 'normal'? Or are there ways of preventing arthritis by looking at our lifestyle?

One reason why so many couples are diagnosed with unexplained infertility is that doctors cannot put it down to a specific, observable medical cause. But infertility is a multifactorial problem and should be investigated that way. That means looking at a variety of issues such as nutrition, alcohol and smoking habits, levels of lead and other toxic metals, pesticides, food additives, genitourinary infections, allergies, stress and other hazards of modern life. That means your partner also needs to take a close look at his health and nutrition as well (since in four out of ten cases of infertility, the problems are on the male side). The fact is that our modern 'unnatural' life style, combined with the nutrient depletion of much of our food, has left many of us deficient in the vitamins and minerals we need for successful babymaking.

There's no doubt that risk of miscarriage increases as we get older. Before the age of 40, the risk of miscarriage is about 15 per cent, and it can rise to about 40 per cent in women over the age of 40, mostly because of genetic abnormalities.

Chromosomal problems

Chromosomal abnormalities are the most common reason for a miscarriage and are usually the result of a one off genetic abnormality in the baby that is unlikely to recur. In other words, Nature is working according to the law of survival of the fittest. When the baby is abnormal, it will try to stop that pregnancy continuing. It is thought that up to half of all miscarriages are due to a genetic abnormality.

The most common chromosomal abnormality diagnosed is a situation where there are three chromosomes in the pair instead of two. Depending on which chromosome pair this happens to, it will give rise to a specific abnormality. Not all abnormalities always end in a miscarriage. For instance, Down's syndrome is caused by an extra chromosome on pair number 21 and for that reason is also called trisomy 21. It is thought that most trisomies are caused by an abnormal division in the egg that occurs before fertilisation.

This may explain why older women have always been thought to have a higher risk of having a Down's syndrome baby, since older women's eggs are more likely to be abnormal. But the Down's Syndrome Association claims that eight out of ten babies with Down's syndrome are born to mothers under the age of 35. The extra chromosome can also come from the man's sperm. So, at the moment, scientists cannot say with any certainty precisely what causes Down's syndrome.

However, there are links between Down's syndrome and mineral deficiencies. For example, people with Down's children have lower levels of zinc and selenium compared with others of the same age (Biol Trace Element Res, 1996; 54: 201-6). It has also been found that, in Down's syndrome, blood levels of the 'antioxidant defence system' enzymes (superoxide dismutase and glutathione peroxidase) are overproduced. Both these enzymes are produced by the body to disarm free radicals. The building blocks for these enzymes include the minerals zinc and selenium.

Selenium is known to protect against chromosomal (DNA) damage by protecting the body against toxins and pollutants, and future research may demonstrate the importance of prospective parents having good levels of this mineral in the months before conception, when both sperm and eggs are maturing. In fact, researchers have already found that women who miscarry have lower levels of selenium in their blood compared with women whose pregnancies go to term (Br J Obstet Gynaecol, 1996; 103: 130-2).

The idea that toxin damage could be implicated in Down's syndrome has been borne out by a study in the wake of the Chernobyl nuclear disaster. Babies born nine months later showed a sixfold increase in cases of Down's syndrome (BMJ, 1994; 30: 158-62). Studies on animals have also shown that it is possible to damage the chromosomes by introducing a toxin (Jennings I, Vitamins in Endocrine Metabolism, William Heinemann Medical Press, 1972).

So the opposite may also be true: that you can protect your chromosomes from damage by minimising your intake of environmental toxins and making sure that you have enough antioxidants to fight unavoidable pollution (like traffic fumes).

Infections

Miscarriage can be caused by infections. Often, it is a one off situation where the mother has caught a severe infection during the early part of pregnancy, and it is unlikely to recur in a subsequent pregnancy. Or the miscarriage could be due to a genitourinary infection which needs to be treated before she conceives again to prevent another miscarriage.

Mr Ronnie Lamont, consultant obstetrician and gynaecologist at Northwick Park Hospital, believes that bacterial vaginosis may trigger miscarriage or premature birth. In a study he conducted with 800 women, he found that those with bacterial vaginosis had five times the risk of late miscarriage (16-34 weeks), and those who delivered early (24-37 weeks) also had the infection.

Other infections that can cause a miscarriage include chlamydia; cytomegalovirus (CMV); herpesvirus, which can reduce a man's sperm count (Alder MW, ABC of Sexually Transmitted Diseases, British Medical Association, 1984); mycoplasmas such as Mycoplasma hominis and Ureaplasma urealyticum; toxoplasmosis; and genital herpes, which can increase the risk of miscarriage by up to 25 per cent. This is why it is vital to be screened for all such infections before you embark on trying to conceive. If you have miscarried, it's also wise to get a check up and have any underlying infections treated so that you don't miscarry again.

Fertility drugs

One of the most commonly prescribed medicines for fertility problems is clomiphene citrate (Clomid), which is used to induce ovulation. Ironically, though it may increase a woman's chances of conceiving, it also increases the chances of a miscarriage by 20-30 per cent (Regan L, Miscarriage, Bloomsbury Publishing, 1997). It is thought that clomiphene can interfere with the womb lining, preventing the fertilised egg from implanting. Other techniques used to induce ovulation, such as gonadotrophin treatment, can also increase the miscarriage rate.

Another overlooked cause is overweight. It is known that obesity increases the risk of miscarriage (Regan, cited above). Problems with excess weight can also be linked with polycystic ovaries (PCO), which can make conception more difficult. Miscarriages are more likely to occur in women with this condition. However, in a study of women with PCO who were asked to change their diet, the rate of miscarriages dropped from 75 per cent to 18 per cent for the same women once they had lost weight (Hum Reprod, 1998; 13: 1502-5).

Hormonal problems

Luteinising hormone (LH) controls the development and release of the egg from the ovary. Women who have high levels of this hormone in the first half of their menstrual cycle seem to have a greater risk of miscarriage. In addition, women with polycystic ovary syndrome (PCOS) have raised levels of LH.

Progesterone is the hormone which maintains the pregnancy during the first few weeks. After the egg has been released from the ovary, the ruptured follicle then develops into the corpus luteum, which produces progesterone. If the egg is not fertilised, after 14 days, the corpus luteum gets the message to continue producing progesterone. Without sufficient levels of progesterone, the pregnancy cannot continue, and that is why antiprogesterone drugs are now used to terminate an early pregnancy without the need for an operation.

Because of this obvious link between progesterone and the maintaining of a pregnancy, many doctors give progesterone as injections or pessaries to prevent a miscarriage. But Professor Lesley Regan, in her excellent book Miscarriage, states that "Injections of hormone, in the early weeks of a pregnancy at risk, may prolong the miscarriage but they cannot reverse it. Low progesterone levels in early pregnancy are the result rather than the cause of miscarriage."

Role of sperm in miscarriage

Because it is the woman who miscarries, greater emphasis has been placed on looking at problems in the female reproductive system. But, if you keep miscarrying when nothing wrong can be found, it is logical to wonder if the problem might lie with your partner's sperm. Early studies have shown an increased risk of miscarriage when sperm abnormalities are present in the partner (Int J Fertil, 1962; 7: 17-21).

A study published in the British Journal of Cancer showed that men who smoke, even if their partners don't, run the risk of fathering children who develop cancers such as leukaemia and brain tumours (Br J Cancer, 1997; 76: 1525-31). The theory is that chemicals in tobacco smoke can damage the DNA in sperm. Taking this one step further, it's easy to see that any changes in DNA in the sperm could lead to a possible increase in miscarriage rate. DNA damage cannot be picked up in a normal semen analysis, so this problem would not be seen during routine fertility investigations.

Apart from the possible increase of abnormalities in babies of women who smoke during pregnancy, there is also an increased risk of miscarriages (Am J Epidemiol, 1998; 108: 470-9). Another study, by Professor Jane Golding of the Royal Hospital for Children in Bristol, highlighted how our own bad habits can affect the next generation. Golding looked at daughters who didn't smoke, but whose mothers had. The daughters subsequently suffered a significantly increased risk of miscarriage (Golding J, presentation at a conference on smoking in pregnancy commissioned by the Health Education Authority, 1994).

Drinking can have an enormous impact on the risk of miscarriages. It is universally acknowledged that alcohol can alter a man's sperm count and cause an increase in abnormal sperm (Am J Clin Pathol, 1950; 20: 814-28). It follows that, if an abnormal sperm

fertilises an egg, Nature will try to get rid of that embryo because it is working through 'survival of the fittest'.

Alcohol is a substance known to cause mutations. Studies have shown that alcohol given to female mice immediately after mating caused severe damage to the chromosomes of one fifth to one sixth of the embryos (The Sunday Times, 31 January 1988). This resulted in a higher percentage of miscarriage or death shortly after birth. Chromosomal damage is a recognised cause of miscarriage.

Research has shown a strong relationship between alcohol and miscarriages. A 1977 study found that women who have a drink every day have a risk of miscarriage 2.5 times higher than non drinkers (N Engl J Med, 1977; 297: 793-6). In this same study, they found that, if the woman was a drinker and a smoker, her risk of having a miscarriage increased by up to four times.

The conclusion from a number of studies on women is that even moderate alcohol consumption works as a reproductive toxin and, as such, can increase the risk of a miscarriage (Lancet, 1980; ii: 176-80).

Caffeine is a stimulant and could therefore be classed as a drug. It has an adverse effect on fertility, and can also cause problems once a woman is pregnant. In a study of 2967 pregnant women, carried out by the Department of Epidemiology and Public Health at Yale University School of Medicine, the researchers found that drinking three or more cups of tea or coffee a day was associated with an increased risk of miscarriage (Am J Epidemiol, 1996; 144: 989-96). Other research has shown that caffeine during pregnancy can increase the probability of chromosomal abnormalities which could lead to a miscarriage.

Since 1980, the US Food and Drug Administration has advised pregnant women to minimise their caffeine intake, citing the dangers of possible miscarriages or having a mentally retarded baby. Some studies suggest that there is a doubly increased risk of fetal loss when as little as one to three cups of coffee are consumed a day. So, the logical advice is to err on the side of caution and avoid caffeine altogether, especially if you have a history of recurrent miscarriages (JAMA, 1993; 270: 2940-3).

Even decaffeinated coffee has been linked to an increased risk of miscarriage (Am J Epidemiol, 1996; 143: 525, abstract no 99) since there is still some caffeine left, even after most of it has been removed. More over, decaffeinated coffee contains two other stimulants theobromine and theophylline which are not removed when coffee is decaffeinated. Also, most decaffeinated coffee has been decaffeinated by a chemical which can remain in the product. An important point to remember is that caffeine comes in many other forms besides tea and coffee. It is there in colas and other soft drinks, as well as in chocolate and pain relieving medications such as headache remedies.

Much fertility treatment involves boosting this or that hormone often by excessive amounts to 'trick' the body. In the case of miscarriages, the doctors may suspect an inadequate level of progesterone or too high a level of LH, and so will use drugs to try to rectify the imbalance. But as with any drug, the treatment will have its own side effects and repercussions. On the other hand, by giving your body the right nutrients, minimising environmental hazards and getting into optimal health, you and your partner can do a great deal to help prevent another miscarriage or one happening in the first place.

!AMarilyn Glenville

Marilyn Glenville's latest book is Natural Solutions to Infertility (Piatkus, 2000, £10.99). She has also given many lectures and workshops on natural menopause. The next workshops will be held in London on 1 July, in Ireland on 2 July, and in Manchester on 8 July. Call 08700 715 715 for details.