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A breech pregnancy or birth is when a baby is positioned or born bottom first, the preferred position being head first. It is said that around 3-5% of pregnant women in the last trimester have a breech baby. We asked one of our Expert Advisory Board members Dr. Michael Rogers 羅傑士醫生 with expertise in the area to explain the matter in an exclusive Healthy Matters interview.
Doctor Michael Rogers has worked in Hong Kong’s public sector for more than 24 years before moving to private practice 10 years ago. He has introduced numerous innovations in obstetrics to Hong Kong, one of them being the external cephalic version (ECV) at term for breech presentation.
In early pregnancy the position of the baby is random with 50% presenting as a breech and 50% as cephalic (head first). As pregnancy progresses the proportion presenting as cephalic increases to around 95% at term.
Most breech presentations will turn spontaneously to cephalic between 32 and 36 weeks of pregnancy. After 36 weeks of pregnancy spontaneous version to cephalic presentation is very uncommon: leaving around 3.5% of babies in breech presentation at term. Conversely, if preterm labor occurs the chances of the baby presenting as a breech are much higher depending on how preterm.
Whilst most breech babies and their mothers are entirely normal, babies with congenital abnormalities (e.g. Spina bifida, Congenital hydrocephalus) or intrauterine growth restriction are more likely to present as a breech. Similarly, women with uterine abnormalities, uterine fibroids, placenta praevia or a history of cesarean section are more likely to have a breech presentation.
Opinions differ regarding the risks of vaginal delivery in breech presentations. Some consider vaginal delivery safe if: the pregnancy is otherwise uncomplicated, the baby weighs less than 3.5kg, is in flexed or complete breech presentation, and the mother is known to have an adequate pelvis (i.e. has delivered vaginally before).
However the Term Breech Trial found a significantly higher neonatal mortality (3x) amongst those planned for vaginal delivery compared to the planned cesarean section group. They concluded (without saying that all women with breech presentation should be delivered by cesarean) that:
“The results of this trial make imperative the need to offer, from a skilled practitioner, external cephalic version (ECV) at term to all suitable women with a breech presentation. Success with ECV will protect both the infant from the risks associated with breech delivery, and the mother from the risks associated with surgical delivery. ECV results in a 58% reduction in relative risk of non-cephalic presentation at birth, and 48% reduction in risk of CS. ECV carries very little risk to the mother, and when carried out under optimal conditions minimal risk to the baby”.
There are a number of non-medical techniques that women can try to encourage spontaneous version of the baby to a cephalic presentation. These include the ‘breech tilt’, a traditional Chinese Medicine treatmentcalled Moxibustion, which involves burning a herbal stick near the corner of your little toe and a chiropractic treatment called the Webster Technique.There is insufficient good quality evidence to suggest these methods actually work but women still like to try.
The external cephalic version (ECV) is the medical manual procedure by which doctors attempt to turn a a breech baby from buttocks or foot first to head first.
External cephalic version is a technique whereby after ensuring the baby is healthy by performing a cardiotocograph (CTG), a tocolytic drug is administered to relax the uterus and manual manipulation of the baby into a cephalic position is attempted under ultrasound control. The success rate of this procedure varies from about 70% in first pregnancies to nearly 100% in subsequent pregnancies.
In a small number of cases (<5%) there may be evidence of fetal distress during or after the procedure which may require proceeding to an immediate C-section. For this reason, ECV should only be attempted in hospital between 36 and 40 weeks of pregnancy. Minimal force should be used to manipulate the fetus as prolonged, forceful attempts are more likely to induce fetal distress.
If ECV fails I currently recommend planned cesarean section at 38-39 weeks of gestation: this maximizes the chances of fetal lung maturity whilst minimizing the chances of labor occurring (with consequent increases in fees charged by the private hospitals).
Cesarean section performed electively before the onset of labor is nowadays a very safe procedure with low wound infection rates and rare complications for mother and baby (although difficulty may be encountered delivering a baby that is deeply engaged in the pelvis leading to occasional fetal trauma).
Emergency cesarean after the onset of labor carries higher risks of infection and fetal trauma during delivery: it should be kept in mind when opting for vaginal birth in breech presentation that emergency cesarean section may still be required. In fact, in the Term breech Trial 43% of women allocated to vaginal birth group actually delivered by cesarean section.
Most of the complications of a C-section delivery are rare. There is an increased chance of a woman requiring a further cesarean section in any subsequent pregnancy and placenta praevia and placenta accreta increase in frequency with each subsequent uterine scar. These two complications may lead to severe maternal hemorrhage, cesarean hysterectomy and even maternal death. In communities such as Hong Kong where family size is usually restricted to one or two children these risks are fortunately very rare.
In my opinion, the risks of cesarean section do not outweigh those of a vaginal breech birth. However, obstetricians have an obligation to minimize the use of cesarean section where they can: ECV should therefore be offered to all patients with term breech presentation unless contraindicated.
Dr. Michael Rogers 羅傑士醫生 received his medical training at the University of Birmingham, UK. He is Honorary Professor at the Chinese University of Hong Kong’s Department of Obstetrics and Gynaecology. He worked for more than 24 years in Hong Kong’s public sector before moving to private practice 10 years ago. In the field of obstetrics Dr. Rogers has published widely in international journals on diabetes, preeclampsia and fetal distress. He was awarded a Doctorate of Medicine by the Chinese University of Hong Kong for his work on preeclampsia.
This article was independently written by Healthy Matters. It is informative only and not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be relied upon for specific medical advice.
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