Older mums: the pros and the cons

Monday, November 21, 2005
Babies these days are more likely to have a mum who is over the age of 30. In fact, the proportion of babies born to women over 30 accounts for 51 percent of the total fertility rate, according to the Australian Bureau of Statistics. There are positive and negative aspects to having children later in life, and here we look at a few of them.

As a generalisation, women over 35 are often more satisfied with their jobs and careers, are financially comfortable and have well established relationships with their partners — all good foundations for starting a family. On the flipside, they have an increased risk of having troubles conceiving, experiencing miscarriages, having children with chromosomal abnormalities and giving birth to twins.

But it is vital to look at these risk factors more closely, because they can still be so low as to not be considered a deciding factor for some women contemplating motherhood. The following figures give approximate risks of chromosomal abnormalities associated with maternal age.

Age of mother at delivery Chance of live-born baby with Down's syndrome Chance of live-born baby with chromosomal abnormality
25 One in 1350 One in 476
30 One in 909 One in 385
35 One in 384 One in 179
40 One in 112 One in 64
45 One in 28 One in 19

"About one in 20 (age 45) is five percent, so you still have a 95 percent chance of having a baby with healthy chromosomes", says Mona Saleh, Genetic Counsellor at the Centre for Genetics Education. Ms Saleh explains the reason for the increased risk is the increased age of the woman's eggs. "For eggs to ovulate and prepare for pregnancy they have to divide … and as women get older that process becomes less efficient. It's believed the chromosomes — in that ovulation process — are not being separated correctly and you can get extra chromosomes sticking together", she says.

Dr Christine Tippett, vice-president of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, adds that the older women get, the more likely they are to run into other pregnancy problems. But she is quick to add that this is a generalisation and many older women don't experience any problems at all. "As a whole group, the difficulties of conceiving start from about 35", she says. "Miscarriage risk increases … the average risk of miscarriage for anyone is one in six, but after 44 the risk is one in two."

Pre-natal screening and pre-natal diagnosis
Non-invasive pre-natal screening is highly common these days and while it doesn't provide a diagnosis of the baby's health, it takes into account factors specific to the woman and can offer a risk figure of chromosomal abnormality, says Ms Saleh. Some of the tests have a 90 percent accuracy rate.

Around 11 weeks a nuchal translucency ultrasound can be performed to look at the thickness of the fold at the back of the baby's neck to screen for chromosomal problems such as Down's syndrome. Blood tests are also conducted to assess specific pregnancy-related chemicals in the mother's blood that alert doctors to that pregnancy being at high or low risk.

Pre-natal diagnosis is more invasive and is often recommended if screening tests identify a baby as being at high risk. At about 11 weeks a CVS (chorionic villus sampling) can be performed. This is where a sample of the placenta is taken through the mother's stomach or cervix. At 15 weeks an amniocentesis can be conducted, which is when a sample of the fluid is taken from around the baby. In each of the tests the chromosomes are examined and the results offer definite diagnoses. There is a one in 200 risk that the diagnostic tests will lead to miscarriage.

Ms Saleh says it's important people realise these tests are optional and that they should think seriously before having them. "If you want that information then that is positive for you whether it is so you can prepare yourself for the birth of a baby with a chromosomal problem or to interrupt the pregnancy", she says. "However, you can potentially put yourself in a position where you need to make a difficult decision."

Things you can do
Mother Nature ultimately decides if and when we fall pregnant, but there are things all prospective mothers can do to help their bodies prepare for a baby.

  • If you are considering pregnancy, it is wise to take folic acid supplements to help prevent spina bifida and other neural tube defects;
  • Stop smoking;
  • Have sex a few times a week to boost the chance of conception, not just once or twice around ovulation;
  • If you are seriously overweight talk to your doctor about getting fitter and healthier;
  • If you are on medications speak to your doctor about their suitability during pregnancy;
  • Ensure your rubella immunisation is up-to-date;
  • Have a pap smear if you haven't had one for a while

Period of adjustment
"Older mums can find the adjustment of having a baby harder than younger mums for two reasons", says Dr Tippett. "Often their lives are very organised and they have a lot of flexibility, especially with regard to recreation. Secondly, they are in a position where they are getting higher in their careers and getting a lot of positive feedback, and suddenly all that stops and they find that adjustment very difficult."

Some older mums can also feel more tired than younger mums, and many experience isolation if they feel they are stuck at home and don't have friends with small children, says Dr Tippett. However, there are things mothers can do to help themselves adjust:

  • Join a mother's group;
  • Get out to see friends with children to avoid feeling trapped at home;
  • Listen to advice, but only follow that which works for you;
  • Make the time to exercise or go for walks;
  • Recognise the need to rest more and go to bed earlier;
  • Keep your options of returning to work open. Once the baby is born, you may not feel ready to go back as soon as originally planned.

Article written by Pamela Wilson, November 21, 2005.

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