The medical definition of a ‘large baby’ is a baby who has macrosomia, otherwise known as a baby who is above 4.5kg in weight at birth, or above 10pd if you don’t follow the metric system. A baby who is 8-9pd/3.65-4kg is not a ‘large’ baby, and is only on the higher end of the ‘normal’ birth weight range for babies (75th-95th percentile on the baby weight charts).
In today’s modern highly medical society many women are being told that a “big” baby will die or be seriously injured if they go to term and birth their baby vaginally, some are even told that they will die or be seriously injured as well if they birth a large baby vaginally. These women are being told that there are no if’s, buts’ or maybe’s and that these things WILL happen if they attempt a vaginal birth at term or just by attempting a vaginal birth in the first place. But the truth is that regardless of how big or small your baby is the majority of the risks apply to everyone, and those risks are still very small when you put them into perspective.
It’s a catch 22, we are misinformed and scared silly with the thought that we might possibly cause our baby or ourselves harm during normal childbirth and if we ignore those scare tactics and still choose to let nature take its course by allowing labour to begin spontaneously when our body and baby are ready for it and initiate it and allow it to progress normally we also then feel guilty if we end up being one of the very small percentage of women that do experience a complication just for choosing something that put ourselves and our baby at risk of that complication. We all must make our own decisions about what risks we feel comfortable taking, and when a baby isn’t involved many of us will willingly take risks with our own lives for the thrill of it or just because we can, but when a baby IS involved we do not like to take extra risks and unfortunately when we are scared by things we have been told, when we are misinformed or coerced by a trained professional into believing that what we were physically designed to do is far too dangerous and we are as a result choosing something that we otherwise wouldn’t choose for ourselves we aren’t actually making the informed decision which is required by law, we are going along with what we have been told to do instead without knowing all of the risks that we already have or all of the new risks we will then be placing upon ourselves by blindly following a “doctors advice” without questioning things. Questioning, demanding truthful, evidence based answers and getting all the information on the risks you may currently have and comparing them to the potential risks of whatever other choices you have been offered is essential to making the informed decision that we are legally required to make prior to signing any consent forms, and once you have done that only then can you make a truly informed decision on something that will affect your whole life, if not mentally then it will affect you physically in some manner, from that moment onwards. The purpose of this blog post is to inform the ready and provide evidence based factual information. The majority of this information is from legitimate research studies, some is from my own experiences of birthing suspected macrosomic babies who turned out only to be “above average” in size between the 75th and 95th percentiles, and from information gained from conversations with my various care providers over the years.
Let’s debunk some myths about the actual, potential, perceived and implied risks of having a larger than average or macrosomic baby both vaginally and via caesarean into perspective:
Myth: My friends and my doctor all told me only big babies develop shoulder dystocia. Is this true?
FALSE: The most commonly mentioned “risk” of having a “large” or macrosomic baby by most doctors is shoulder dystocia or “sticky shoulders” where the babies shoulder becomes stuck behind the pubic bone or it’s shoulders have difficulty moving through the pelvis and become “sticky”. Contrary to popular belief, a ‘small’ baby (a baby who is under 3kg at birth) is just as likely to have shoulder dystocia or ‘sticky shoulders’ as a larger baby, it all depends on the babies position as he/she moves through the birth canal, how patient the delivery suite staff are (and how prone to panic they are too, sometimes even the most experienced staff will panic if they think that something is wrong or that something is taking too long) and the mothers position as she delivers.
Myth: My doctor says my pelvis is too small to birth my baby vaginally. Is this true?
FALSE: For the vast majority of women in the western world this is false, although there are some rare exceptions. A misshapen or too small pelvis, called Cephalo-Pelvic Disproportion, is very rare and true diagnosis is confined to those with skeletal abnormalities from chromosomal or genetic disorders, those who have suffered from severe malnutrition resulting in rickets (caused by very low vitamin d levels which are essential for calcium absorption and proper bone growth), those with what is called an android pelvis (a pelvis that is shaped similar to a man’s pelvis which makes it almost impossible to birth vaginally although there are also exceptions to this) or those who have broken their pelvis at some point in their life. An incorrect diagnosis of Cephalo-Pelvic Disproportion can be given if your baby is malpositioned and doesn’t descend resulting in an emergency caesarean (and in some cases it can be given after a “failure to progress” diagnosis that resulted in an emergency caesarean to make the reason for the caesarean easier for a mother to accept) which can also be caused by a twisted pelvis that, I am pleased to say, can be fixed by a qualified chiropractor before and during subsequent pregnancies. If the mother is flat on her back during labour and birth not only will her pelvic width be reduced, making it harder for the baby to move into the birth canal, but her baby will also be fighting against gravity as it makes its way into the world and will not be able to manoeuvre as effectively as it could if mum was using gravity to help her birth her baby safely and the way nature built us to birth our children. There are various positions which can help your baby move into a better position before and during labour, if you have a doula she or he can help you with them, or you can do them with your partner and some you can even do by yourself, you can find these position by clicking on the Spinning Babies Website link located in the references section at the end of this blog post. If after trying these positions your baby is still in the same position as he or she was before you tried them then don’t despair, many babies will move on their own during labour and birth, and even when they don’t a vaginal birth is still possible in most cases with the right support behind you.
Myth: My doctor told me my baby is too large for me to birth at full term and I need to be induced early because I have a high risk of my baby getting stuck in the birth canal. Is this true and what are my chances if I go to full term?
FALSE: Your doctor has not given you all of the facts and also has not explained the actual risks to you properly, when you next see your doctor ask to see the actual research statistics on shoulder dystocia for both small and large babies. You have the same risk as everyone else wanting a vaginal birth. The chance of your baby getting shoulder dystocia is approximately 0.2% to 3% with an average of 1 in every 200 births (these percentages cover everyone regardless of if their baby is “large” or small, and are about the same as the risk of uterine rupture in a mother hoping for a Vaginal Birth/VBAC after 1, 2 and even up to 5 cesareans, just to put it into perspective for you).
Myth: My doctor told me that if I try to birth my large baby vaginally I will haemorrhage and die. I am very scared of this happening, please tell me is this true or is it a scare tactic?
FALSE: This is not exactly true so it is classed as false in this instance as you have the same risk as anyone else of haemorrhaging during birth, regardless of your babies size, and with the current medical treatments for post partum haemorrhage your risk of dying from this is very low and is the same as pretty much everyone else (apart from those with existing bleeding disorders who are at higher risk anyway and are usually encouraged to birth vaginally because of the higher risks of severe haemorrhage during a caesarean). According to the WHO (2005) approximately 11% of all live births (both vaginal and caesarean) regardless of baby’s size will result in a severe post partum haemorrhage, that is 11 out of every 100 women who will lose over 1 litre of blood after birth. The vast majority of these women who experience a severe post partum haemorrhage will survive thanks to modern medicine, so the risk of you dying from a haemorrhage is quite low.
Myth: Lots of babies are born quite large these days. It’s more common to have a large baby than a small or average sized baby/ True or False?
FALSE: This is quite simply false. According to the 2003 statistics only 1.8% of all babies born in Australia in 2003 were macrosomic (born weighing 4.5kg or more). This number may have increased slightly up to 2-4% between then and now but I have been unable to find any statistics regarding average rates of macrosomia for 2013 or 2014 at this point in time.
Myth: A large baby (suspected to be macrosomic and over 4-4.5kg) is not a common cause of induction or elective caesarean. Surely doctors wouldn’t suggest those things if they weren’t necessary? True or False?
FALSE: With an average caesarean rate of 1 in every 3 births within Australia it doesn’t surprise me that a lot of inductions and primary caesareans are as a result of a suspected macrosomic baby. If you take a look in a general pregnancy and parenting forum or similar facebook group you will see a lot of women scheduled for early induction or a caesarean because a late pregnancy ultrasound scan has measured their babies as being larger than average and therefore “too big to birth vaginally at full term or post estimated due dates”. In the US alone a suspected macrosomic baby is approximately the 4th most common reason for an induction (which has its own risks not related to birthing a macrosomic baby and makes it more likely for shoulder dystocia to occur), and approximately the 5th most common reason for an elective caesarean (which has its own risks as well not related to macrosomia or vaginal birth). These numbers are not much different within Australia.
Myth: My doctor told me that I would either tear badly in my perineal area if I attempted a vaginal delivery or would need an episiotomy to help get my baby out. Is this true?
FALSE: This is false, an episiotomy should only ever be used as a last resort if baby needs to come out very quickly and you are fully dilated and haven’t torn naturally and baby isn’t descending properly. For the vast majority of women an episiotomy is not needed, and it is far better for the mother to tear naturally as in general a natural tear will heal quicker and cleaner than an artificial cut. You are more likely to have a small tear or only have grazing from a vaginal delivery if you and baby are left well alone, you are allowed to birth in whatever way feels comfortable to you and as long as you are both happy and healthy. You have the same risk of having a severe perineal tear during a vaginal birth with a small baby as you do with a macrosomic baby, and there is no difference in the rates of 3rd and 4th degree tears between small babies and macrosomic babies born vaginally, with your overall risk of a 3rd or 4th degree tear being between 0.2% and 0.6% according to Weissmann-Brenner et al. 2012 (notice that this general risk is the same or smaller than the risk of shoulder dystocia mentioned earlier). According to Sheiner et al. 2005, a vacuum delivery (ventouse extraction) increases your risk of a severe tear by up to 11 times (0.2-2.2%) for all women expecting small, average or macrosomic babies and your risk of a severe tear with the use of forceps increases by up to 39 times (0.2-7.8%).
Myth: My doctor told me that because my baby is measuring so big if I don’t go into labour on my own before 38/39 weeks my baby will be stillborn. Is this true?
FALSE: This information that your doctor has given you is most definitely false. While the general risk of stillbirth is slightly higher from 40 weeks gestation onwards, your risk is just as high prior to 38 weeks gestation and is lower between 39 and 41 weeks. The general risks are still low at under 3% and they are not related to baby’s size. There is no evidence that having a larger baby increases your risk of stillbirth. Your overall risk of stillbirth with a larger baby is the same as everyone else who is low risk and at the same gestation as you are.
Myth: My doctor told me that I need to be induced or book an elective caesarean early to prevent complications. Is this true?
FALSE: While there is a small risk of shoulder dystocia, severe haemorrhage (over 1 litre of blood loss post birth), stillbirth and severe perineal tear when birthing a baby vaginally regardless of size, these potential “complications” apply to everyone regardless of the size of their baby. The most common complications from having a larger baby stem from inductions and cesareans themselves, including maternal and/or fetal injury, haemorrhage (most commonly haemorrhage requiring a blood transfusion), clotting disorders, maternal infection and baby having breathing problems.
Myth: Someone told me that if my baby is measuring big on the ultrasound that I’m more likely to end up with a caesarean. Is this true?
TRUE: This is true, but not because your baby is measuring larger than average. It is because a doctor is more likely to insist on an early induction before your baby or your body are ready for labour or because your doctor will insist on an elective caesarean, especially if you have already had one or more caesareans prior to your current pregnancy. According to Blackwell et al. 2009b if a baby is suspected of being macrosomic physicians are more than twice as likely to diagnose “stalled labour” or “failure to progress” and perform a caesarean (35%) when compared to physicians supporting women who were not suspected of having a macrosomic baby (13%), also according to Sanchez-Ramos et al. 2002 if you are suspected of having a macrosomic baby and wait for labour to begin spontaneously you only have an 8% risk of needing an emergency caesarean compared to a risk of 17% if you are induced early.
Myth: I was told that my baby is measuring very big on my 37 week ultrasound. My doctor told me the weight was accurate. Is this true?
FALSE: This is false. According to Chauhan et al. 2005 ultrasound weight estimates for normal and above average are only approximately 50% accurate, meaning that 25% of in-utero baby weight estimates will be below the weight estimated, 25% will be higher than the weight estimated and only 50% of the total will be exactly or close to the estimated weight, and ultrasounds for babies estimated to weigh 4.5kg or more were only 20-30% accurate, meaning that only 20-30% of all weight estimates will be exactly or close to the baby’s birth weight and the remaining 70-80% will be either lower or higher than the estimated weight. Not good statistics when you think about it, your baby’s weight could end up being much lower than estimated, or much higher, and without an ultrasound you would never have known what it could possibly be until after your baby was born.
Myth: But ceasareans prevent permanent nerve injury from shoulder dystocia. True or False?
FALSE: This is false. According to Rouse et al. 1996, in a low risk mother with no diagnosis of diabetes, in order to prevent one permanent nerve injury in a baby from shoulder dystocia, 2,345 women suspected of carrying a macrosomic baby would need to have an elective caesarean for a suspected large baby estimated at weighing over 4kg. That’s a lot of unnecessary caesareans given that only 11.725 of those women would experience shoulder dystocia during birth, and only 3.2 of those 11.725 babies would receive permanent nerve damage leaving 8.525 babies with transient nerve damage that will heal itself, so looking at it like that your risk of it even happening at all is less than 0.0015%, or approximately 1.3 in every 1000 vaginal births. Also according to Rouse et al. 1996 it was also estimated that for every 3.2 permanent nerve injuries to a baby that were prevented by the above mentioned caesareans there would be 1 maternal death caused by complications from the surgery itself, or approximately 1 maternal death in every 7504 scheduled caesarean births that could have been prevented.
Myth: Vaginal birth is safer than a caesarean for low risk women. True or False?
TRUE: For non-diabetic women vaginal delivery of a suspected macrosomic baby is safer for them, their baby and future pregnancies than an elective caesarean section is, and for diabetic women a vaginal delivery is also the ideal, but with the added risks from potentially uncontrolled or badly controlled diabetes an early induction or elective caesarean are often recommended. However, you always have the right to refuse an early induction or elective caesarean even when you are high risk, the decision is always yours to make.
Myth: For a diabetic woman a third trimester ultrasound, usually done around 36-37 weeks gestation, is more accurate than it is for everyone else. True or False?
TRUE: This is partially true in that ultrasounds are only slightly more accurate in predicting a larger than average or macrosomic baby in diabetic women (Type 1, Type 2 and Gestational Diabetes), this is most likely due to the fact that diabetic women are more likely to have larger babies, especially if their diabetes is not well controlled. This could easily be considered false though.
Myth: Ultrasound during late pregnancy is the only way to diagnose macrosomia. True or False?
FALSE: This is false, as ultrasounds are only 20-50% accurate in the first place, and late term ultrasounds (ultrasounds conducted in the third trimester usually between gestational weeks 36 and 37) are notoriously inaccurate as the estimated weight of your baby is based on leg, arm, belly and head measurements, for example if your baby has long legs the estimated weight will be higher, or if your baby has a larger belly then the estimated weight will also be higher (baby belly measurements change day to day due to how much amniotic fluid is within the stomach, how much amniotic fluid is surrounding the baby while the measurement is being taken and how many different sonographers are measuring and their respective experience), and likewise if your babies legs and/or belly are measuring smaller your babies estimated weight will be lower as well. Because every baby, just like the rest of us, is different and has different genetic factors affecting growth, how much fat is absorbed and stored, how large they grow etc all measurements given by ultrasound are subject to error and should only be used as guidelines for measuring potential growth and only show an estimate of the growth made up to that point in time. Basically this means that your baby might stall in growth for another 2 weeks or so after the ultrasound estimating that your baby will large and over 4kg and then your baby will be born at 39-41 weeks weighing only 3.4kg, or if you are induced early shortly after your ultrasound you might find that you have birthed a 3.8kg baby who was only supposed to be measuring at 3kg according to the ultrasound! What I am trying to say is that the only accurate way to diagnose macrosomia is to weigh the baby after delivery, anything before birth is just an estimate based on a series of measurements that are compared to a baseline series of measurements in a computer and are then calculated and converted to provide an estimated answer based on those equations and they are NOT a guarantee.
I hope this blog post has been helpful, below you can find a list of the various links used in the research of this blog post, feel free to pay them a visit and see the information and statistics for yourself. I highly recommend Evidence Based Birth for up to date information based on actual scientific research.
Jenna Edgley
Birth Doula and Placenta Encapsulator
FOOTPRINTS & RAINBOWS
References:
http://brochures.mater.org.au/Home/Brochures/Mater-Mothers-Hospital/Shoulder-dystocia
http://www.uptodate.com/contents/shoulder-dystocia-risk-factors-and-planning-delivery-of-at-risk-pregnancies
http://www.pphprevention.org/pph.php
http://www.babycenter.com.au/a1015615/macrosomia-big-baby
http://evidencebasedbirth.com/evidence-for-induction-or-c-section-for-big-baby/
http://www.spinningbabies.com
In today’s modern highly medical society many women are being told that a “big” baby will die or be seriously injured if they go to term and birth their baby vaginally, some are even told that they will die or be seriously injured as well if they birth a large baby vaginally. These women are being told that there are no if’s, buts’ or maybe’s and that these things WILL happen if they attempt a vaginal birth at term or just by attempting a vaginal birth in the first place. But the truth is that regardless of how big or small your baby is the majority of the risks apply to everyone, and those risks are still very small when you put them into perspective.
It’s a catch 22, we are misinformed and scared silly with the thought that we might possibly cause our baby or ourselves harm during normal childbirth and if we ignore those scare tactics and still choose to let nature take its course by allowing labour to begin spontaneously when our body and baby are ready for it and initiate it and allow it to progress normally we also then feel guilty if we end up being one of the very small percentage of women that do experience a complication just for choosing something that put ourselves and our baby at risk of that complication. We all must make our own decisions about what risks we feel comfortable taking, and when a baby isn’t involved many of us will willingly take risks with our own lives for the thrill of it or just because we can, but when a baby IS involved we do not like to take extra risks and unfortunately when we are scared by things we have been told, when we are misinformed or coerced by a trained professional into believing that what we were physically designed to do is far too dangerous and we are as a result choosing something that we otherwise wouldn’t choose for ourselves we aren’t actually making the informed decision which is required by law, we are going along with what we have been told to do instead without knowing all of the risks that we already have or all of the new risks we will then be placing upon ourselves by blindly following a “doctors advice” without questioning things. Questioning, demanding truthful, evidence based answers and getting all the information on the risks you may currently have and comparing them to the potential risks of whatever other choices you have been offered is essential to making the informed decision that we are legally required to make prior to signing any consent forms, and once you have done that only then can you make a truly informed decision on something that will affect your whole life, if not mentally then it will affect you physically in some manner, from that moment onwards. The purpose of this blog post is to inform the ready and provide evidence based factual information. The majority of this information is from legitimate research studies, some is from my own experiences of birthing suspected macrosomic babies who turned out only to be “above average” in size between the 75th and 95th percentiles, and from information gained from conversations with my various care providers over the years.
Let’s debunk some myths about the actual, potential, perceived and implied risks of having a larger than average or macrosomic baby both vaginally and via caesarean into perspective:
Myth: My friends and my doctor all told me only big babies develop shoulder dystocia. Is this true?
FALSE: The most commonly mentioned “risk” of having a “large” or macrosomic baby by most doctors is shoulder dystocia or “sticky shoulders” where the babies shoulder becomes stuck behind the pubic bone or it’s shoulders have difficulty moving through the pelvis and become “sticky”. Contrary to popular belief, a ‘small’ baby (a baby who is under 3kg at birth) is just as likely to have shoulder dystocia or ‘sticky shoulders’ as a larger baby, it all depends on the babies position as he/she moves through the birth canal, how patient the delivery suite staff are (and how prone to panic they are too, sometimes even the most experienced staff will panic if they think that something is wrong or that something is taking too long) and the mothers position as she delivers.
Myth: My doctor says my pelvis is too small to birth my baby vaginally. Is this true?
FALSE: For the vast majority of women in the western world this is false, although there are some rare exceptions. A misshapen or too small pelvis, called Cephalo-Pelvic Disproportion, is very rare and true diagnosis is confined to those with skeletal abnormalities from chromosomal or genetic disorders, those who have suffered from severe malnutrition resulting in rickets (caused by very low vitamin d levels which are essential for calcium absorption and proper bone growth), those with what is called an android pelvis (a pelvis that is shaped similar to a man’s pelvis which makes it almost impossible to birth vaginally although there are also exceptions to this) or those who have broken their pelvis at some point in their life. An incorrect diagnosis of Cephalo-Pelvic Disproportion can be given if your baby is malpositioned and doesn’t descend resulting in an emergency caesarean (and in some cases it can be given after a “failure to progress” diagnosis that resulted in an emergency caesarean to make the reason for the caesarean easier for a mother to accept) which can also be caused by a twisted pelvis that, I am pleased to say, can be fixed by a qualified chiropractor before and during subsequent pregnancies. If the mother is flat on her back during labour and birth not only will her pelvic width be reduced, making it harder for the baby to move into the birth canal, but her baby will also be fighting against gravity as it makes its way into the world and will not be able to manoeuvre as effectively as it could if mum was using gravity to help her birth her baby safely and the way nature built us to birth our children. There are various positions which can help your baby move into a better position before and during labour, if you have a doula she or he can help you with them, or you can do them with your partner and some you can even do by yourself, you can find these position by clicking on the Spinning Babies Website link located in the references section at the end of this blog post. If after trying these positions your baby is still in the same position as he or she was before you tried them then don’t despair, many babies will move on their own during labour and birth, and even when they don’t a vaginal birth is still possible in most cases with the right support behind you.
Myth: My doctor told me my baby is too large for me to birth at full term and I need to be induced early because I have a high risk of my baby getting stuck in the birth canal. Is this true and what are my chances if I go to full term?
FALSE: Your doctor has not given you all of the facts and also has not explained the actual risks to you properly, when you next see your doctor ask to see the actual research statistics on shoulder dystocia for both small and large babies. You have the same risk as everyone else wanting a vaginal birth. The chance of your baby getting shoulder dystocia is approximately 0.2% to 3% with an average of 1 in every 200 births (these percentages cover everyone regardless of if their baby is “large” or small, and are about the same as the risk of uterine rupture in a mother hoping for a Vaginal Birth/VBAC after 1, 2 and even up to 5 cesareans, just to put it into perspective for you).
Myth: My doctor told me that if I try to birth my large baby vaginally I will haemorrhage and die. I am very scared of this happening, please tell me is this true or is it a scare tactic?
FALSE: This is not exactly true so it is classed as false in this instance as you have the same risk as anyone else of haemorrhaging during birth, regardless of your babies size, and with the current medical treatments for post partum haemorrhage your risk of dying from this is very low and is the same as pretty much everyone else (apart from those with existing bleeding disorders who are at higher risk anyway and are usually encouraged to birth vaginally because of the higher risks of severe haemorrhage during a caesarean). According to the WHO (2005) approximately 11% of all live births (both vaginal and caesarean) regardless of baby’s size will result in a severe post partum haemorrhage, that is 11 out of every 100 women who will lose over 1 litre of blood after birth. The vast majority of these women who experience a severe post partum haemorrhage will survive thanks to modern medicine, so the risk of you dying from a haemorrhage is quite low.
Myth: Lots of babies are born quite large these days. It’s more common to have a large baby than a small or average sized baby/ True or False?
FALSE: This is quite simply false. According to the 2003 statistics only 1.8% of all babies born in Australia in 2003 were macrosomic (born weighing 4.5kg or more). This number may have increased slightly up to 2-4% between then and now but I have been unable to find any statistics regarding average rates of macrosomia for 2013 or 2014 at this point in time.
Myth: A large baby (suspected to be macrosomic and over 4-4.5kg) is not a common cause of induction or elective caesarean. Surely doctors wouldn’t suggest those things if they weren’t necessary? True or False?
FALSE: With an average caesarean rate of 1 in every 3 births within Australia it doesn’t surprise me that a lot of inductions and primary caesareans are as a result of a suspected macrosomic baby. If you take a look in a general pregnancy and parenting forum or similar facebook group you will see a lot of women scheduled for early induction or a caesarean because a late pregnancy ultrasound scan has measured their babies as being larger than average and therefore “too big to birth vaginally at full term or post estimated due dates”. In the US alone a suspected macrosomic baby is approximately the 4th most common reason for an induction (which has its own risks not related to birthing a macrosomic baby and makes it more likely for shoulder dystocia to occur), and approximately the 5th most common reason for an elective caesarean (which has its own risks as well not related to macrosomia or vaginal birth). These numbers are not much different within Australia.
Myth: My doctor told me that I would either tear badly in my perineal area if I attempted a vaginal delivery or would need an episiotomy to help get my baby out. Is this true?
FALSE: This is false, an episiotomy should only ever be used as a last resort if baby needs to come out very quickly and you are fully dilated and haven’t torn naturally and baby isn’t descending properly. For the vast majority of women an episiotomy is not needed, and it is far better for the mother to tear naturally as in general a natural tear will heal quicker and cleaner than an artificial cut. You are more likely to have a small tear or only have grazing from a vaginal delivery if you and baby are left well alone, you are allowed to birth in whatever way feels comfortable to you and as long as you are both happy and healthy. You have the same risk of having a severe perineal tear during a vaginal birth with a small baby as you do with a macrosomic baby, and there is no difference in the rates of 3rd and 4th degree tears between small babies and macrosomic babies born vaginally, with your overall risk of a 3rd or 4th degree tear being between 0.2% and 0.6% according to Weissmann-Brenner et al. 2012 (notice that this general risk is the same or smaller than the risk of shoulder dystocia mentioned earlier). According to Sheiner et al. 2005, a vacuum delivery (ventouse extraction) increases your risk of a severe tear by up to 11 times (0.2-2.2%) for all women expecting small, average or macrosomic babies and your risk of a severe tear with the use of forceps increases by up to 39 times (0.2-7.8%).
Myth: My doctor told me that because my baby is measuring so big if I don’t go into labour on my own before 38/39 weeks my baby will be stillborn. Is this true?
FALSE: This information that your doctor has given you is most definitely false. While the general risk of stillbirth is slightly higher from 40 weeks gestation onwards, your risk is just as high prior to 38 weeks gestation and is lower between 39 and 41 weeks. The general risks are still low at under 3% and they are not related to baby’s size. There is no evidence that having a larger baby increases your risk of stillbirth. Your overall risk of stillbirth with a larger baby is the same as everyone else who is low risk and at the same gestation as you are.
Myth: My doctor told me that I need to be induced or book an elective caesarean early to prevent complications. Is this true?
FALSE: While there is a small risk of shoulder dystocia, severe haemorrhage (over 1 litre of blood loss post birth), stillbirth and severe perineal tear when birthing a baby vaginally regardless of size, these potential “complications” apply to everyone regardless of the size of their baby. The most common complications from having a larger baby stem from inductions and cesareans themselves, including maternal and/or fetal injury, haemorrhage (most commonly haemorrhage requiring a blood transfusion), clotting disorders, maternal infection and baby having breathing problems.
Myth: Someone told me that if my baby is measuring big on the ultrasound that I’m more likely to end up with a caesarean. Is this true?
TRUE: This is true, but not because your baby is measuring larger than average. It is because a doctor is more likely to insist on an early induction before your baby or your body are ready for labour or because your doctor will insist on an elective caesarean, especially if you have already had one or more caesareans prior to your current pregnancy. According to Blackwell et al. 2009b if a baby is suspected of being macrosomic physicians are more than twice as likely to diagnose “stalled labour” or “failure to progress” and perform a caesarean (35%) when compared to physicians supporting women who were not suspected of having a macrosomic baby (13%), also according to Sanchez-Ramos et al. 2002 if you are suspected of having a macrosomic baby and wait for labour to begin spontaneously you only have an 8% risk of needing an emergency caesarean compared to a risk of 17% if you are induced early.
Myth: I was told that my baby is measuring very big on my 37 week ultrasound. My doctor told me the weight was accurate. Is this true?
FALSE: This is false. According to Chauhan et al. 2005 ultrasound weight estimates for normal and above average are only approximately 50% accurate, meaning that 25% of in-utero baby weight estimates will be below the weight estimated, 25% will be higher than the weight estimated and only 50% of the total will be exactly or close to the estimated weight, and ultrasounds for babies estimated to weigh 4.5kg or more were only 20-30% accurate, meaning that only 20-30% of all weight estimates will be exactly or close to the baby’s birth weight and the remaining 70-80% will be either lower or higher than the estimated weight. Not good statistics when you think about it, your baby’s weight could end up being much lower than estimated, or much higher, and without an ultrasound you would never have known what it could possibly be until after your baby was born.
Myth: But ceasareans prevent permanent nerve injury from shoulder dystocia. True or False?
FALSE: This is false. According to Rouse et al. 1996, in a low risk mother with no diagnosis of diabetes, in order to prevent one permanent nerve injury in a baby from shoulder dystocia, 2,345 women suspected of carrying a macrosomic baby would need to have an elective caesarean for a suspected large baby estimated at weighing over 4kg. That’s a lot of unnecessary caesareans given that only 11.725 of those women would experience shoulder dystocia during birth, and only 3.2 of those 11.725 babies would receive permanent nerve damage leaving 8.525 babies with transient nerve damage that will heal itself, so looking at it like that your risk of it even happening at all is less than 0.0015%, or approximately 1.3 in every 1000 vaginal births. Also according to Rouse et al. 1996 it was also estimated that for every 3.2 permanent nerve injuries to a baby that were prevented by the above mentioned caesareans there would be 1 maternal death caused by complications from the surgery itself, or approximately 1 maternal death in every 7504 scheduled caesarean births that could have been prevented.
Myth: Vaginal birth is safer than a caesarean for low risk women. True or False?
TRUE: For non-diabetic women vaginal delivery of a suspected macrosomic baby is safer for them, their baby and future pregnancies than an elective caesarean section is, and for diabetic women a vaginal delivery is also the ideal, but with the added risks from potentially uncontrolled or badly controlled diabetes an early induction or elective caesarean are often recommended. However, you always have the right to refuse an early induction or elective caesarean even when you are high risk, the decision is always yours to make.
Myth: For a diabetic woman a third trimester ultrasound, usually done around 36-37 weeks gestation, is more accurate than it is for everyone else. True or False?
TRUE: This is partially true in that ultrasounds are only slightly more accurate in predicting a larger than average or macrosomic baby in diabetic women (Type 1, Type 2 and Gestational Diabetes), this is most likely due to the fact that diabetic women are more likely to have larger babies, especially if their diabetes is not well controlled. This could easily be considered false though.
Myth: Ultrasound during late pregnancy is the only way to diagnose macrosomia. True or False?
FALSE: This is false, as ultrasounds are only 20-50% accurate in the first place, and late term ultrasounds (ultrasounds conducted in the third trimester usually between gestational weeks 36 and 37) are notoriously inaccurate as the estimated weight of your baby is based on leg, arm, belly and head measurements, for example if your baby has long legs the estimated weight will be higher, or if your baby has a larger belly then the estimated weight will also be higher (baby belly measurements change day to day due to how much amniotic fluid is within the stomach, how much amniotic fluid is surrounding the baby while the measurement is being taken and how many different sonographers are measuring and their respective experience), and likewise if your babies legs and/or belly are measuring smaller your babies estimated weight will be lower as well. Because every baby, just like the rest of us, is different and has different genetic factors affecting growth, how much fat is absorbed and stored, how large they grow etc all measurements given by ultrasound are subject to error and should only be used as guidelines for measuring potential growth and only show an estimate of the growth made up to that point in time. Basically this means that your baby might stall in growth for another 2 weeks or so after the ultrasound estimating that your baby will large and over 4kg and then your baby will be born at 39-41 weeks weighing only 3.4kg, or if you are induced early shortly after your ultrasound you might find that you have birthed a 3.8kg baby who was only supposed to be measuring at 3kg according to the ultrasound! What I am trying to say is that the only accurate way to diagnose macrosomia is to weigh the baby after delivery, anything before birth is just an estimate based on a series of measurements that are compared to a baseline series of measurements in a computer and are then calculated and converted to provide an estimated answer based on those equations and they are NOT a guarantee.
I hope this blog post has been helpful, below you can find a list of the various links used in the research of this blog post, feel free to pay them a visit and see the information and statistics for yourself. I highly recommend Evidence Based Birth for up to date information based on actual scientific research.
Jenna Edgley
Birth Doula and Placenta Encapsulator
FOOTPRINTS & RAINBOWS
References:
http://brochures.mater.org.au/Home/Brochures/Mater-Mothers-Hospital/Shoulder-dystocia
http://www.uptodate.com/contents/shoulder-dystocia-risk-factors-and-planning-delivery-of-at-risk-pregnancies
http://www.pphprevention.org/pph.php
http://www.babycenter.com.au/a1015615/macrosomia-big-baby
http://evidencebasedbirth.com/evidence-for-induction-or-c-section-for-big-baby/
http://www.spinningbabies.com
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