Down's Syndrome and other chromosome abnormality testing

With more women having children after the age of 35 years, testing for Down's Syndrome ( Mongolism ) and other chromosome abnormalities has become even more important. The test with the highest accuracy of course would be the amniocentesis, however this is an invasive procedure and it would not be practicle to perform this on every pregnant woman above 35 years. Testing has evolved from the triple test (measuring 3 markers in the blood at 15 weeks onwards ) to tests which are done in the first trimestor ie 11 -14 weeks.

In my practise, I will start with looking for the nasal bone between 11and 14 weeks. An absent nasal bone is strongly suggestive of a chromosome problem.  I will do two tests. The first is the measurement of the nuchal translucency ( this is the fluid at the back of the foetal neck which is present in all foetus's but is greatly increased in one with a chromosome disorder ). This should be <2.5mm. There are false positives and I increase the accuracy by combining this test with measurement of 2 markers in the blood, one a hormone beta-HCG and a protein PAPP-A. The combination of these tests is called the Oscar test. This gives a predictive accuracy of 95% for a chromosome abnormality.

If the tests are positive then an amniocentesis or CVS is offered. The alternative is to retest with a triple test and nasal bone measurement at 16 weeks, and if positive an amniocentesis should be done as the likelihood of a chromosome abnormality is high.

Normal delivery or caesarean section?

Obstetricians have always been taught that normal delivery was best, unless there was an indication for a caesarean section. It was assumed that every pregnant woman would want to have a normal delivery. But is normal delivery really better? The caesarean section rates have always been on the rise and now account for about 1 in 3-4 deliveries. I would say that after 25+ years of practising obstetrics, it would appear to me that a caesarean section delivery has a lot more going for it than a normal delivery. I will probably be shot down by many fellow obstetricians for this statement. However I have seen way more complications arising from a normal delivery than caesarean sections. Many pregnant women are unaware that a normal delivery has a higher risk to the baby ( this is only logical since a baby would be more prone to foetal distress having to traverse the female pelvis in its passage to this world, and a long labour may leave both mother and baby exhausted and more prone to potential hazards ). One would argue that recovery is faster with a normal delivery. This may not necessarily be true for a long labour or one with multiple vaginal tears.

Pregnant women now want to be more involved in decision making with regard to mode of delivery and this is a good thing so that a proper informed decision can be made. The obstetricians role is now more of a facilitator and educator in the antenatal care and delivery of the baby. Having weighed the pros and cons joint decisions are made, sometimes even with the input of of various family members.

Premature labour

One of the many concerns I often get asked is will my baby come early? The question should actually be will my baby be premature or preterm. Labour anytime before 37 weeks would be considered as premature. It is common for the baby to come between 37 and 40 weeks but this is not a problem. The incidence of preterm labour is about 12% of all pregnancies. The most common causes are infections eg strept B, trauma to cervix eg after an abortion or cone biopsy, multiple pregnancies, poor nutrition, inadequate rest, chronic medical illnesses eg asthma. In a large number, the cause is unknown. The preterm labour tends to recur with each pregnancy.

Your obstetrician may want to perform a vaginal scan in the early or late second trimestor to determine the length of your cervix if there is a history of preterm labour or other risk factors. A short cervix ( between 10-21mm ) indicates a high risk of preterm labour.

Rest and good nutrition are very important. It is my practise to start the pregnancy with utrogestan as very often early threatened miscarriage and later preterm labour are associated with a lack of the pregnancy hormone, progesterone. Utrogestan is micronised progesterone and is very safe for use in pregnancy. I will continue this until 36 weeks. I have many patients with recurring miscarriages and preterm labour, when put on utrogestan achieve a full term and healthy baby. Tocolytics such as ventolin can be added if there are signs of excessive uterine contractions or impending labour.It also appears that consuming moderate amounts of  fish prevents preterm labour and tends to prolong the pregnancy in a recent study.

Bleeding in early pregnancy

The most common problem in the first 12 weeks of pregnancy is bleeding. This can be very alarming and distressing but the good thing is that although common, the majority resolve without adverse effect on the foetus. The miscarriage rate is about 1:5 overall.

Bleeding is most often due to insufficient pregnancy hormone, progesterone. The pregnancy then threatens to dislodge from the uterine wall resulting in bleeding. If the bleeding is slight, it will appear as a brown stain but if more serious there will be passage of clots associated with abdominal cramps.

It is prudent to visit your gynaecologist early in the pregnancy ( best time is 5-6 weeks) especially if there has been a previous pregnancy with bleeding ( since bleeding in pregnancy tends to repeat itself with each pregnancy ). Treatment can then be instituted before too much damage has been done. It is especially not wise to come after repeated episodes of bleeding as each subsequent bleed may jeopardise the foetus. A scan can be done to determine if the foetal heartbeat is seen. This is usually detectable at 6 weeks pregnancy. Hormone therapy can then be instituted. If there is heavy bleeding, or a history of more than one miscarriage, it is my practice to administer a course of HCG injections + utrogestan. If only slight bleeding,  bed rest and utrogestan is administered. With hormonal treatment, the bleeding should stop within a few days and if it persists more than a week, should be reviewed to exclude other causes for the bleeding.

Nausea & Vomiting in pregnancy

Most pregnant women will experience some degree of nausea and vomiting (NVP). It usually starts at about 6-8 weeks when the hormone levels are at its highest. Some 20%, the lucky few will not have this experience. You can tell if you will or will not experience NVP by whether you are prone to car or sea sickness!. Nevetheless if you get it it is a good sign in that the pregnancy is likely to be on going and the risk of miscarriage lower. The converse however does not hold true. If severe NVP is present this may sometimes be due to twin pregnancies!

If severe it can be quite debilitating and creates depression and worry whether the baby is getting sufficient nutrition. Overall the foetus is quite hardy and unless really severe to the point of dehydration, is unlikely to affect the foetus. You should initially try eating small meals several times a day, avoiding situations which might trigger off the NVP such as strong smells, noisy surroundings, certain foods. NVP is also called morning sickness but it rarely occurs in the morning and usually before or after midday. If you are able to after eating lying down often helps, or chewing on ice chips. Sea bands round the wrist from the pharmacy may help.

If more severe, your gyne may want to give you two medications that are the gold standard for treatment of NVP without side effects or effects on the foetus. Pyridoxine (vitamin B6) up to 40mg/day or a combination of pyridoxine and an antihistamine such as phenergan often will make alot of difference. It is the occasional patient who will require admission and an intravenous drip. Most NVP resolve by 12 weeks unless there are associated gastric and intestinal problems such as gastritis, gastric or duodenal ulcer.

Flying, radiation and pregnancy

With all the news about radiation and the nuclear catastrophe in Japan, I thought it appropriate to visit this topic. Firstly pregnant women should not get unduly alarmed. Although air travel has been on the increase, there does not appear to be an increase in the number of children with abnormalities or developing leukaemia. air travel exposes the foetus to cosmic radiation. The amount of radiation is low, less than that of a normal chest xray. however, the longer the exposure the greater the potential risk. Long haul flights (>4 hours) would increase the risks. Foetal cells are at greater risk of damage than adult cells. In the first trimestor and up to 18 weeks, the risks would be that of miscarriage, damage to the chromosomes resulting in foetal abnormalities especially the brain. after 28 weeks, the foetus is fully formed. The risks then is that of cancer eg leukaemia in the future.

To avoid the potential risks to your baby, it would therefore be prudent not to travel up to 18 weeks, and if you have to travel, confine it to short haul flights. Minimise the number of flights overseas throughout your pregnancy. http://www.safety.duke.edu/radsafety/fdose/fdrisk.asp

Diet and pregnancy

Its always been the case that your obstetrician will tell you that its not good to put on too much weight. Well, from the mothers point of view this makes sense since excessive weight gain leads to diabetes, bigger babies and more difficult births. However, there appears to be new evidence from a study that showed that low carbohydrate diets and dieting in general during pregnancy is not good for your baby as it can lead to obesity in your child later in lofe. the study showed that pregnant women who were on a low carbohydrate diet increased the methylation of the gene which is responsible for obesity in childhood. http://diabeted.diabetesjournal.org/content/early/20-0979.abstract  So little weight gain and dieting in pregnancy can lead to fat kids later on. This is logical since starvation causes 'survival mode' to kick in allowing for increased fat stores in foetus. the answer would probably lie somewhere in between, eat a sensible diet high in protein and a moderate amount of complex carbohydrates. Oily fish such as wild salmon would be a good choice in addition tolean meats and vegetables. Aim to gain about 1-2kg per month. Weight gain will not be even but an overall weight gain of 12-15 kg would be about right.