Dr. Patrick Chia featured in The Star 2007Good antenatal care a mustALTHOUGH women over 35 have higher pregnancy and childbirth risks, the majority have healthy babies – thanks to advances in medical care. It also helps when one is aware of the risks associated with later childbearing so that one can make informed decisions.
Consultant gynaecologist and obstetrician Dr Patrick Chia says that women from the ages of 30 to 35 years experience a drop in fertility up to 20% below the maximum and from ages 35 to 40, the decrease is 25% to 50%.
“This could be due to a decline in ovulation, decrease in the frequency of intercourse and the presence of medical and gynaecological conditions, such as endometriosis, which interferes with conception.
“If conception doesn’t occur after six months of trying, a woman over 35 should seek medical help,” he says.
Dr Patrick Chia: ‘If conception doesn’t occur after six months of trying, a woman over 35 should seek medical help.’There are potential risks, such as diabetes and high blood pressure, which can develop for the first time in pregnancy, especially in women above the age of 35.
Dr Chia says that placental problems such as Placenta praevia (low lying placenta), is eight times more common in the older mother. She is also more likely to have problems with labour and delivery as foetal distress and prolonged labour become more common. The risk of having a caesarean section can be as high as 43% in those over 35 years.
“The rate of miscarriages is also significantly higher – the risk is 9% for women aged 20 to 24, rising to 20% at age 35 to 39 and more than 50% by the age of 42,” he adds.
As a woman ages, the risk of bearing a child with chromosomal defects increases. The most common is Down syndrome where the child is mentally sub-normal and may suffer physical abnormalities. The risk for a 25-year-old woman is about one in 1,250, rising gradually to one in 400 at 35 years.
Similarly, there is an increased risk of other less common chromosomal defects, such as Edward syndrome (an extra chromosome 18) and Patau syndrome (an extra chromosome 13). Other foetal problems that may occur include low birth weight and premature delivery, and an increased risk of stillbirth.
The facts and figures are disconcerting but, even at 40, the odds of having a healthy baby are in the woman’s favour.
“Antenatal tests should be considered if there is a family history of genetic disease, a previous baby with a birth defect or a recent exposure to a serious infection such as rubella or toxoplasmosis,” says Dr Chia.
The sheer number of antenatal tests available for the expectant mother is enough to make her head spin.
“Although the choice of antenatal tests is a personal one, couples ought to weigh all the pros and cons, including religious and cultural implications. Seek out local experts who will be able to help in the decision-making process.”
One should also bear in mind that such tests can’t detect all problems and a negative test doesn’t guarantee a perfectly healthy baby.
There are two types of antenatal tests: screening and diagnostic.
An ultrasound scan utilises high frequency sound waves to produce an image of the baby on a monitor/screen. Ultrasound used in early pregnancy helps determine viability and detect multiple pregnancies, gestational age and assess the health of the baby.
The nuchal scan (done within the window period of 11 to 14 weeks), is 83% accurate in screening for Down syndrome. A detailed scan performed at 20 weeks will detect most structural defects in the baby, such as spina bifida, omphalocele (protrusion of abdominal contents such as liver and gut through an anterior abdominal wall defect) and diaphragmatic hernia.
A maternal serum biochemistry (blood test) can also be done in the first or second trimester to measure different chemicals in the blood to detect Down and Edward syndromes.
A more familiar procedure is the amniocentesis, which involves the insertion of a long needle and the extraction of amniotic fluid after 15 weeks of pregnancy. Another option is Chorionic villous sampling (CVS), which is essentially a placental biopsy, performed after 10 weeks and under ultrasound guidance.
Antenatal screening tests (such as the ultrasound scan) for foetal abnormalities are usually non-invasive and don’t cause any harm to the baby. In contrast, diagnostic tests are usually invasive as it involves sampling with a needle and carries a procedure-related risk of miscarriage.
“The first eight weeks of pregnancy are critical in a baby’s development. Good antenatal care should include education on pregnancy and childbirth, counselling and support,” concludes Dr Chia.