Reducing the Risk of Birth Defects

AIMS Journal, 1995/6, Vol 7 No 4

A major study from Norway has shown mothers who have already had a baby with a birth defect may increase their chances of having a perfect baby next time by moving elsewhere before they get pregnant again!

The authors loolt at the records of babies bom to nearly 372,000 women between 1967 and 1989. The firstborn babies of almost 9,200 women had a birth defect, such as club feet, abnormalities of the genitals, limbs, heart, cleft lip or cleft palate. Unfortunately mothers whose first child had a problem are at greater risk than other women of having a later child with a similar defect - two and a half times, in fact. Mostly the increased risk was caused by the fact that the same defect was more likely to occur in the next child - 7.6 times the risk of women whose first child was normal.

They also have a slightly higher risk of having a child with a different type of defect - 1.5 times that of other women.

However, those who stayed in the same district for both pregnancies had the highest risk of all - 11.6 times the risk of other mothers. Those who moved to another district alter their first baby was born halved the increased risk to 5.1.

AIMS COMMENTS

This strongly suggests that only part of the risk of having a baby with a defect is genetic. A maior part of the risk is environmental and many teratogens (i.e. substances which injure the development of the baby in the womb) have not yet been identified.

So perhaps women who have given birth to a baby with a defect, or who have had a termination for an abnormal baby, should consider moving to another district even temporarily if they plan to have another pregnancy, but we suggest they should get genetic advice first. However couples who move, change more than the water they drink or the air they breathe. They are often also changing lifestyle in other ways - possibly better quality housing, and a different job where one parent is not exposed to the same chemicals. This certainly needs more investigation. What differences were there between couples who moved and those who did not?

Meanwhile this study highlights the point we made in our study on ultrasound“’. Detection of abnormal babies by scans and offering termination does not tackle the basic problem. While obstetricians and health authorities see the economic benefit of reducing health care costs by aborting affected babies, parents want to conceive healthy children in the first place. A policy primarily concentrating on “detect and abort' has deflected attention from identifying and dealing with primary causes of damage, which we need to seek more rigorously.”

[STOP PRESS: A more recent study has shown that moving does NOT reduce the risk of having another baby with cleft lip or palate.]

Jean Robinson

REFERENCES

1. Lie, R.T. et al. A population based study of the risk of recurrence of birth defects. NEW ENGLAND JOURNAL OF MEDICINE 1994 Vol 331 pp1-4
2. Beech B. and Robinson J. Ultrasound ? Unsound AIMS 1994.