Can we prevent abnormalities in a second pregnancy?

Dear Dr Mitchell,

My wife had a stillbirth at 33 weeks. The baby had birth defects: the heart was outside, cleft palate, encephalocele… This was very disturbing. What can we do to prevent subsequent occurrence?

I am truly sorry to learn about the stillborn baby that you and your wife had at 33 weeks gestation. The birth defects cleft palate, encephalocele and heart defect may all be associated with a chromosomal abnormality.

Women have millions of eggs and men produce millions of sperm. However, some of them are abnormal. As you grow older — above 35 years old — the chance of having an abnormal baby increases significantly and fertility also decreases. Birth defects or abnormal foetuses may also be seen in younger women, but are less common.

There are tests that can be done in pregnancy to determine the risk for chromosomal abnormalities and birth defects. In the first 14 weeks, a detailed ultrasound to measure the nuchal translucency will help to increase the suspicion for Down’s syndrome (Trisomy 21). Ultrasounds can also detect abnormalities in the brain and spinal cord, heart and other organs; and a detailed ultrasound done at 18–20 weeks is a routinely done examination recommended for all women. This is called the anomaly scan.

Defects in the heart may indicate a chrosomal abnormality. Four dimensional ultrasounds are widely available and increase the ability to detect structural abnormalities in the foetus, including cleft palate.

A blood test can also be done using the mother’s blood in the first trimester to detect DNA from foetal cells and then this is subsequently tested to determine the presence of chrosomal abnormalities. This test is more commonly done at about 16 weeks when the detection rate is significantly higher. This is called the Harmony screen. This is available locally at the CARIGEN Unit at The University of the West Indies, Mona campus. Other blood tests using maternal blood include the triple and quad screen. The triple screen measures the level of oestradiol, alpha fetoprotein and beta human chorionic gonadotrophic (BHCG) in the mother’s blood. The quad screen measures those three hormones in addition to the hormone INHIBIN. This is then correlated with gestational age of the foetus and determines the risk for the offspring to have defects in the spinal cord and brain and chromosomal abnormalities. A detailed ultrasound can then be done to try to identify any structural defects.

An amniocentesis is a procedure that involves inserting a needle into the amniotic sac around the foetus and removing amniotic fluid that is then subsequently tested to determine the presence of a chrosomal abnormality. This is usually done at about 16 weeks. This is invasive, however, and may sometimes result in the loss of the pregnancy despite the presence of a normal foetus. With the availability of sensitive blood tests and high-resolution ultrasound, the need for amniocentesis is significantly reduced.

The way forward in reducing the risk of birth defects is to have your children at an early age, before 40 years, have a healthy diet and use folic acid supplements before and during pregnancy to reduce the risk of defects in the brain and spinal cord. It is also important to control medical problems such as diabetes mellitus before pregnancy and maintain tight control of blood glucose throughout the pregnancy to reduce the risk of birth defects. Pregnancy should be planned at a time when the blood sugar is perfectly controlled, and early antenatal care should be sought to ensure tight control of the blood sugar.

In most cases the chance of recurrence of these birth defects is extremely low, so you should definitely try again as soon as possible and seek early antenatal care with your obstetrician who will advise you further.

Best wishes.

Dr Sharmaine Mitchell is an obstetrician and gynaecologist. Send questions via e-mail to allwoman@jamaicaobserver.com; write to All Woman, 40-42 1/2 Beechwood Ave, Kingston 5; or fax to 968-2025. All responses are published. Dr Mitchell cannot provide personal responses.

DISCLAIMER:

The contents of this article are for informational purposes only, and must not be relied upon as an alternative to medical advice or treatment from your own doctor.