Anastasia Baker: With many women choosing to have babies later in life, they need to remember that conceiving become steadily more difficult after 35. Their may also have more problems during their pregnancy. Professor Philip Steer is a Consultant Obstetrician of the Chelsea and Westminster Hospital in London. Welcome to you.

Prof. Philip Steer: Thank you.

Anastasia Baker: So what problems do older women have when they're trying to conceive?

Prof. Philip Steer: Well, the main problem is that a woman is born with all the eggs she will ever have. Then when she goes through the menarche and goes to puberty, she will start to ovulate regularly, but is in the limited supply of those eggs. By the time that she reaches 35, her ability to produce the right hormones and so on to ovulate regularly will start to decline. So that by the time a woman is 40, she is going to have about half the chance of getting pregnant that as much she was 20. By the time she is 45, that's down to 1-10%.

Anastasia Baker: So is 20 the best age to really conceive the -- young but --?

Prof. Philip Steer: Ideally -- yes, in terms of conceiving, 20-30 is probably ideal. In terms of actually carrying the baby, we know that mothers from 30-35 also do very well and moreover they have better skills at looking after the baby after it's born. So probably the ideal age group for having baby is 25-35.

Anastasia Baker: So are older women likely to have more abnormal babies then?

Prof. Philip Steer: Yes, the biggest problem, once you get above 35, is the increasing risk of having a baby with Down syndrome. This is what we called Trisomy 21.

Anastasia Baker: But there are lots of tests out there that can detect Down syndrome.

Prof. Philip Steer: Yes, but they are all screening tests. And all of them have a significant false-negative rate. So even with the best test, you're going to pick up about 85% of affected babies. So even with the best screening test, they are still going to be some babies who will be born unexpectedly with Down syndrome.

Anastasia Baker: What is a false-negative test?

Prof. Philip Steer: A false-negative test is where the test of pH to give you a normal result, but the baby is, in fact, abnormal.

Anastasia Baker: Alright, okay. What can you do about that?

Prof. Philip Steer: Well, there's nothing really you can do during the pregnancy. What we need to distinguish clearly between a screening test, which is what most women have. So either a scan at 12 weeks, it's called a Nuchal Translucency Screen, or a blood test at about 18 weeks, it's called a Serum Screen or the anomaly scan at around 18-22 weeks which will pick up about half the babies with Down syndrome. These are all screening tests, which means that you can pick up between them, 85-90% of babies with Down syndrome.

But some Down syndrome babies look normal on a scan and they are often actually the healthiest than the babies when they're born. So there isn't necessarily a way that you'll be able to pick them up. What you then need to think about doing is a diagnostic test which is actually putting a needle in, taking fluid from around the baby, culturing the cells and actually looking at the chromosomes to see if this child has the normal number of chromosomes or has an extra chromosome making it Down syndrome. This is called the diagnostic test.

Now clearly, this is much more reliable in terms of picking the babies up, but unfortunately, about one to a half of percent, that's 1 in 1-200 babies will be lost from the side effect of the test. So unlike screening tests, it's more risky.

Anastasia Baker: So why is it 35? Why is that the turning point? Why is that the key age?

Prof. Philip Steer: Yeah. It's not actually really 35. The risk of having a Down's baby goes up from the age of about 20 onwards as the eggs get older. So you're born with all the eggs you have and so as you expose it to radiation and background and X-rays and ultraviolet, all sorts of rays --

Anastasia Baker: Other than Down syndrome, what are the abnormalities that can occur?

Prof. Philip Steer: Well, the Down syndrome is the commonest chromosomal abnormality. These days, spina bifida and Anencephaly, that's the baby not having the head developed properly, relatively uncommon, because of people improving their diet and taking folic acid. There are about 3500 described congenital malformation syndromes, all of which are individually rare, but when you add them together, that means that about 2% of babies at 12-14 weeks will actually have a significant congenital abnormality, that's one in fifty.

Anastasia Baker: So what in these women listening to you today, age 35 and over, freaking out. What can you do to reassure them?

Prof. Philip Steer: Right, I think the only practical approach is to think about this before you get pregnant, decide whether you want to take the option of a screening test or if, for example, you are a mother of age 43 or 44, you might want to get straight to the diagnostic test and risk losing a normal baby in order to be really sure that your baby isn't abnormal at least from a Down syndrome point of view. So you need to make -- that's a personal decision, it's based on all sorts of religious, ethical, personal considerations.

Having decided that, when you're pregnant, what you should then do is take the screening test, take the diagnostic test that you have decided that you won't. Then having made every effort to check whether the baby is normal, just say, well, it's now in the lap of the gods, there is nothing more we can do to influence it, even with the best techniques. About one in 100-150 babies will still be born with a significant abnormality. But there is nothing we can do about that. So we then have to just go into what we call acceptance mode and trying to get on with their lives.

Anastasia Baker: So the statistics are, one in two, one in three, over 35?

Prof. Philip Steer: No, the risk of Down syndrome, the average risk in the population is about one in 700.

Anastasia Baker: Right.

Prof. Philip Steer: When you get to 35, it goes up to double of that about one in 350. Then when by the time you're 40, it's about 1% or one in a hundred. By the time you're 45, it's one in ten, so 10%. So that is really -- so you can see the rate of abnormality starts to increase quite markedly. So it's not just that it suddenly starts increasing the risk, the risk goes up gradually in your 20s, a bit faster in your early 30s. It starts to accelerate in your late 30s and then goes up very steeply in your 40s.

Anastasia Baker: How do you find older women cope during that pregnancy? Do they have more issues, more problems than younger woman?

Prof. Philip Steer: Right. The most important thing is that as we all get older, and that includes me, we're more lightly to develop conditions such as high blood pressure or diabetes. Both of these can be important complications of pregnancy.

Anastasia Baker: So if you've never had those before, these can suddenly manifest themselves during the pregnancy?

Prof. Philip Steer: No, what I'm talking about is women who are already known to be diabetic or have high blood pressure or at least are detected as having high blood pressure or diabetes when they become pregnant. Some woman are not aware of it. That's much more likely if you are 40 than if you are 20. Very few women of 20, if they haven't been diabetic since they're teens, as long as they feel healthy, they're very unlikely to have what we call Type 2 diabetes.

Anastasia Baker: Why is that? What are the reasons for that?

Prof. Philip Steer: The reason for that is that some organs like the lungs or the heart or the kidneys have a lot of spare reserve and most people know you only need one kidney to get on perfectly, happily. But some organs like the pancreas which makes the insulin which controls our blood sugar, only just produces enough insulin in most of us. So as we get older and we gradually are less efficient, our insulin production gradually declines and blood sugar tends to go up. So that's why older people are much more likely to become diabetic.

In some groups in the population, for example, Asian mothers, as many as 30% of people in their 50s and 60s will become diabetic because of this effect. So the older you are the more likely you are to develop this diabetic tendency. So that's why we screen older mothers very carefully for blood pressure and diabetes. It's also a little bit more common for older mothers to have either preterm births, multiple pregnancies is also more common, and also not just diabetes but also high blood pressure.

Anastasia Baker: Multiple pregnancy is there if they've had intervention for --

Prof. Philip Steer: No, even prettily, naturally, women tend to --

Anastasia Baker: Older women tend to have more twins.

Prof. Philip Steer: More frequently, because their ovulation mechanism is no longer working quite as efficiently. So they have a higher rate of twins.

Anastasia Baker: Are older women more likely to need a cesarean section?

Prof. Philip Steer: It's true that most of the body tissues gradually stiffen up and certainly I'm aware of that at my age and that's also true of the pelvic muscles and the ligaments and the joints and so on. So it is a bit more difficult as when we get older to give birth naturally. Also, because they are more likely to develop high blood sugars in diabetes, their babies tend to be bigger on average. So that can give rise to difficulties with birth. So we know that women over 40, for example, the average cesarean section rate is going to be 40%-50% compared with perhaps 20%-25% with women in their 20s in current practice.

Anastasia Baker: Then that's just the exhausting factor, isn't that, when you have had the baby, older woman find it's tiring.

Prof. Philip Steer: It's very tough, not only it's hard work being pregnant, particularly, if you have a multiple pregnancy, but it's equally hard work running around after a one or two-year-old. Naturally, older women just find that a little bit more stressful.

Anastasia Baker: So do you find they take longer to recover from childbirth?

Prof. Philip Steer: They tend to. The plus side is the older mothers are frequently very highly motivated. For many of these mothers, they're often well-educated, they've had plenty of life experience, it's something they really want to do. Therefore they're very positive about their pregnancy. So I find that in my practice, quite often that compensates quite nicely for some of the physical difficulties.

Anastasia Baker: So what about mothers out there who maybe thinking, Gosh! I don't want a baby yet, but then I don't want to have all these risks that happen after 35. What would you suggest to them?

Prof. Philip Steer: Well, probably the most practical solution at the moment is to think about having your babies actually earlier at 35 or earlier, simply because of this problem that you may find it impossible to get pregnant later and then you'll have to have IVF. There have been experiments with taking biopsies of the women's ovary and freezing them and then giving them their eggs back later, so that when they're 40, there eggs are still in 20.

Anastasia Baker: Do you find women are doing that? That seems an obvious way around this problem, if you've got a woman who is very involved in her career and doesn't want to have a baby at 20.

Prof. Philip Steer: Sure, but then she needs an operation to remove parts of the ovary. The ovary has to be frozen and then of course all the IVF techniques have to work. So it's not a guarantee, but it does mean that older woman, and we know that from ovum donation, are now having babies in their late 40s and even early 50s. I've certainly looked after a considerable number of women of this age.

In general, if they are otherwise healthy, once they've succeeded in getting pregnant, the pregnancy itself is usually quite straightforward.

Anastasia Baker: So you're saying, you've looked after 50-year-old women using that treatment, she has frozen her egg?

Prof. Philip Steer: Not with freezing the eggs, but with ovum donation when she has got the eggs from a younger woman. It's not the mother's body has cells which makes it difficult to conceive or carry a pregnancy when she is 45, it's the fact that her eggs are older and they don't sort of work as well. So if you take a young egg and you put it in the older mum, their pregnancy is usually very good. It's the egg which is the problem not the mum.

Anastasia Baker: So tell us about this, at what age was she, she was 50, that was the oldest --

Prof. Philip Steer: Well, I looked after a number of women in their late 40s, early 50s.

Anastasia Baker: What's the oldest woman you have looked after?

Prof. Philip Steer: 52.

Anastasia Baker: 52. She had pregnancy and was perfectly fine.

Prof. Philip Steer: She had a cesarean but it was otherwise completely uncomplicated.

Anastasia Baker: And she had borrowed some younger woman's eggs?

Prof. Philip Steer: She had. Yes. Not borrowed it, she wasn't intended to give it back.

Anastasia Baker: She is fine now, how old is the baby now?

Prof. Philip Steer: He's about six now.

Anastasia Baker: She must be tired then.

Prof. Philip Steer: Yes, yeah, sure -- no, no she is delighted and she keeps me in touch with how he's getting on and she's having a wonderful time being a mum.

Anastasia Baker: What would be the oldest age for this to be a safe procedure? Can we do it on a 60-year-old woman and the 70?

Prof. Philip Steer: It has been done in women over 60.

Anastasia Baker: Wow! In this country?

Prof. Philip Steer: I don't think yet.

Anastasia Baker: Is there a cutoff?

Prof. Philip Steer: Not really, there isn't a fundamental limit and it's simply a question of the other thing, of course, you then have to think about is how old is the mother going to be when the child goes to school or university or will she live to see her grandchildren?

Anastasia Baker: But what would you say, if a 62-year-old woman came into your office one day and said, this is what I want? Would you be legally obliged to carry out this procedure?

Prof. Philip Steer: No, in the United Kingdom, most fertility units are fairly cautious about this. There aren't any absolutely rigid age limits.

Anastasia Baker: So what would you do then? You could do it.

Prof. Philip Steer: Yes, and mostly it's a question of what we call counseling. In other words, you need to talk to the woman very, very deeply about what her motivations are, what the risks are in terms of carrying the pregnancy, but more particularly, what's going to become when the child is 15 years old and he has got a mother who is 70 or 75? Those are the issues, I think, that need to be going through with that mother in great depth. My experience would be that most women, when they really understand the implications are unlikely to go ahead with pregnancies at such an advance stage.

But we will have to remember that we're all living longer these days. And there are an awful lot of very, very fit women at 50 who years ago would -- being 50 many years ago would have been a big problem, but now for many women, it's relatively young still.

Anastasia Baker: But do you see the future as being one where people will start taking their eggs at 20 or 30 and having them frozen?

Prof. Philip Steer: I think, probably the main thing that will stop, it will be the cost. Getting pregnant naturally is actually cheap. For a lot of people it doesn't actually cost anything. It's bringing up the child that's the most expensive thing. For women who have infertility problems actually getting pregnant, and with IVF treatment around 6000-8000 pounds a cycle, this is not something --

Anastasia Baker: Yes, this is not a possibility for older women.

Prof. Philip Steer: So I think the main thing that will restrict, it will probably be simply economics.

Anastasia Baker: So what advice would you give to that 35-plus-year-old woman out there watching?

Prof. Philip Steer: Right, if she really wants to have a baby, I would say to her, do think about getting on with it. There is never a perfect time to have a baby. We all experience this problem or I'm not quite ready yet, but don't leave it too late and then become disappointed and find that you can't have your own baby. So get on with it.

The second thing is, it's a good idea to go for a quick screen beforehand. Get your blood pressure checked. Cut your blood sugar particularly if you have a family history of diabetes or any of these other problems. Discuss what sort of tests you'd like on the baby once you have conceived. Then when you are pregnant, go to a hospital or go and see an obstetrician who has got experience of dealing with older mothers and make sure that you get checked out thoroughly. Then once all that is done, the great majority of older mothers will have a very successful and happy pregnancy.

Anastasia Baker: Professor Steer, thank you very much for coming here today.

Prof. Philip Steer: Delighted!