Professor Phil Steer answers your questions on baby development, such as checking for abnormalities.
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Anastasia Baker: Being pregnant is an exciting time in any woman's life, but also a time of anxiety, particularly with regard to whether her fetus is growing properly in the womb. Well, with me in the studio is Professor Philip Steer, Consultant Obstetrician at the Chelsea and Westminster Hospital in London. He is here to answer questions on fetal development. Welcome! So what are the main reasons why a baby might not be growing very well in the womb? Professor Philip Steer: Well, there are a number of major reasons. One is that the baby might not be normal, might have congenital abnormalities. That's, of course, the reason we do so many scans, particularly around 18 to 22 weeks of pregnancy to check, so that if the baby is not growing very well, then we will do another scan partly to measure the size of the baby, but also to check that there isn't an abnormality in the baby that we've missed. Another important cause of the baby being small is the mother who's seriously under weight or has some medical disease which prevents her pumping blood through the placenta adequately. So it's important that women get themselves into good shape and as fit and healthy as possible before they actually embark on a pregnancy. Another important cause is a condition we call preeclampsia. This is pregnancy-induced high blood pressure. This occurs in about 2% to 3 % of first pregnancies in a severe form and in about 10% in a mild form. If women develop this condition, they are more likely to have a baby that's not growing properly. So, we will screen them for that. Anastasia Baker: If you've presumably got a history of this sort of thing in your family, that would be something else you take into consideration when you're initially doing and screening moms. Professor Philip Steer: Sure! Yes! The most valuable indicator of a woman who's likely to have a small baby is actually that she's had a small baby before or a baby that hasn't grown properly before. Anastasia Baker: And in those cases, then what would you do? Scan her more? Professor Philip Steer: Yes, normally we would scan the baby regularly about once every four weeks. As long as the baby is growing normally, up the growth charts, and keeping pace with the growth as it should be, not because necessarily it's very small or very large, it can be small and healthy, but then it will grow normally just along the small line as it were or the large line. Anastasia Baker: I suppose, it's one that stops growing. Professor Philip Steer: It's when it stops growing is when we're concerned. So that will be done about every four weeks. If the growth starts to tail off and it's not as good as it should be, then we start looking at the blood flow in the placenta. We actually look at the blood vessels in the umbilical cord leading to the placenta and we look at the ratio of how fast the blood is flowing when the baby's heartbeats compared to when it's not. Looking at that ratio, we can actually work out whether the placenta is allowing the blood to go through easily enough or not. We can do that every week. If that then becomes abnormal, we will then start monitoring the baby's heartbeats sometimes 2 or 3 times a day on what we call fetal heart monitor for up to 40 minutes at a time. Then if that becomes abnormal, that means the baby is not getting enough oxygen and we should deliver it. So, there's sort of staged progress of this type of investigation. Anastasia Baker: Those ultrasounds scans you were talking about, can they be a health risk to a baby in a womb? Professor Philip Steer: There is no known risk currently to ultrasound. There have been a number of studies over the years which have suggested that they might reduce the incidents of right-handedness. They don't make baby left-handed, but the babies are slightly less likely to be right-handed. So they become a bit more ambidextrous. There is no known harmful effect in relation to that. Apart from that, nothing else has shown up, but nonetheless,