From what weight is a baby considered very tall?The average weight of a newborn baby is around 3.4 pounds. Babies weighing more than 4 kilograms at birth are considered to be larger than average and are therefore macrosomes (NCCWCH 2008, RCOG 2012). If you have an extremely tall baby of 4, 5 kg or more, the risk of certain complications increases. Although many women give birth to very large babies without any problems, it is likely that they need a little help (HSCIC 2015).
About eight percent of babies born to normal-weight mothers are macrosomes at birth, but if you are overweight your risk of having a macrosome child increases (Bolz et al, 2014).
How do I know if I'm going to have a big baby?It's hard to find out if your baby is really macrosome while still in the womb (RCOG 2012). You only have clarity when you know the birth weight.
Your midwife or doctor may have a first indication of your baby's size if you are larger than average pregnant women. An ultrasound scan can give an initial indication of how tall your baby really is. However, this study is not always accurate in advanced pregnancy. The results may vary by as much as fifteen percent between ultrasound weight and actual birth weight (RCOG 2012).
If the examination reveals that your baby is above average for your pregnancy week, your midwife and doctor will probably keep track of your blood glucose levels. He / she can monitor if you develop gestational diabetes (NCCWCH 2008).
What could be the reason my baby is so tall?The largest factor is likely to be gestational diabetes or pre-existing diabetes (Alberico et al 2014, NCCWCH 2008, Heiskanen et al 2006). You are also more likely to get a big baby if:
- you have a high body mass index (BMI) at the beginning of your pregnancy (Ahmed et al 2012, Alberico et al 2014, NCCWCH 2008, Bhattacharya et al 2007, Heiskanen et al 2006, Salihu et al 2011,). They gained a lot of weight during pregnancy (Ahmed et al 2012, Alberico et al 2014).
- You are more than two weeks above your calculated due date (Heiskanen et al 2006). They have increased significantly between two pregnancies (Villamor and Cnattingius 2006) or have not lost weight after a previous pregnancy (Bogaerts et al 2013).Your origins also play a role (Wilson et al 2014) and even your baby's gender can make a difference, boys are often taller than girls (Ahmed et al 2012, Heiskanen et al 2006, Di Renzo et al 2007, Sojo et al., 2010). Even if you already have a baby, especially a big baby, you are more likely to have a big baby in another pregnancy. (Heiskanen et al 2006, Walsh et al 2007).
- But even though some of these factors apply to you, it does not automatically mean that you'll get a larger than average baby.
- For example, your midwife or doctor will rate your risk as low if you are not suffering from diabetes (Alberico et al 2014). The truth is that the differences in birth weight often can not be explained.
How will it affect the birth when I have a big baby?
A big baby can very well be born vaginal. However, if your baby has an estimated birth weight of more than 4.5 lbs, you will also discuss with you the option of having a cesarean section to prevent complications.
Logically, delivery may take longer in such a case. And in one out of five vaginal births of very large babies, a supported birth becomes necessary (HSCIC 2015). Other complications may be an increased risk of severe postpartum blood loss (Ahmed et al 2012, Weissmann-Brenner et al 2012) and a major perineal tear (RCOG 2007). If you have already born without complications, you have the advantage: It is likely then that you will give birth again without any complications (Heiskanen et al 2006).
If your baby weighs more than 4, 5 kg, there is a one in thirteen risk of having a shoulder dystocia at birth. This risk increases to one in seven if your baby weighs over 5 kg (Rossi et al 2013). This means that the baby's shoulder is stuck after the head has already been pushed out, and that happens more often when the baby is very tall (RCOG 2012). This situation is rare, but dangerous and requires the immediate attention of doctors and obstetricians.If this happens, a team of midwives and physicians will be available to help you have a vaginal delivery. These experts should then give clear instructions as to when the mother should press and when not and in what position she should go. For most women, switching to a different position is enough to free the baby's shoulder (RCOG 2012).
If you are more than average, your midwife may want to start your labor early. If she wants to do that, ask her for the reasons. For most women with large babies, early labor onset has no demonstrable benefit - neither to the mother nor to the child.(RCOG 2012).
The only exception is if you have diabetes. Induced childbirth after 38 weeks of pregnancy or elective cesarean section reduces the risks of giving birth to a large baby (RCOG 2012).
If your midwife believes you have a large baby and recommends induction or Caesarean section, you should discuss with her the potential risks compared to a vaginal delivery. It can be helpful to talk about your hopes, fears and options (Reid et al 2014).
Will my big baby suffer from health problems after birth?
Most big babies are healthy. Only if your baby's birth actually has a shoulder dystocia can it cause some problems afterwards. If the shoulder gets stuck during the press phase and needs to be released, it can damage the muscles and nerves in the shoulder and arm. (RCOG 2012).
This type of nerve damage occurs in between 2 and 16 percent of babies with shoulder dystocia occurring during delivery (RCOG 2012). The probability increases when the baby needs a lot of help during childbirth or is very tall (RCOG 2012). But even if a baby suffers a nerve damage, it is very likely to recover completely (RCOG 2012, Wall et al 2014). And even if the collarbone is broken during childbirth, in most cases this will heal without any problems (Paul et al 2013).
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