A woman recently gave birth to a baby boy who is 59 cm tall and weighs 7.3 kg.
Angerson Santos was born by caesarean section at the Padre Colombo hospital, in Parintins in the Brazilian Amazon.
The world’s heaviest baby on record weighed 10.2 kg when he was born in 1955 in Italy.
For comparison, newborn boys weigh an average of 3.3 kg and girls 3.2 kg.
The term used to describe these “giant babies” is macrosomia (Greek for “big body”).
Any newborn weighing more than 4 kg, regardless of gestational age, is considered a macrosomic baby.
Macrosomic babies account for about 12% of births. In women with gestational diabetes (high blood sugar during pregnancy), this percentage increases to between 15% and 45% of births.
Why happens?
Certain factors increase a woman’s risk of giving birth to a giant baby, one of them being body weight.
Obese mothers are twice as likely to have a newborn with macrosomia.
And excessive weight gain during pregnancy also increases the risk of macrosomia.
Gestational diabetes is another risk factor. Doctors at the Padre Colombo hospital attribute Angerson’s size to the fact that her mother has diabetes.
Part of this condition is due to increased insulin resistance in the mother during pregnancy (even in those without gestational diabetes), which increases the amount of glucose that crosses the placenta to the fetus and causes the fetus to grow in excess.
The condition also helps lipids (fats) enter the placenta, providing the baby with more “fuel” for growth.
A late pregnancy also increases the chances of having a macrosomic baby.
A maternal age greater than 35 years makes it 20% more likely that the baby has macrosomia.
The age of the father also counts. A paternal age greater than 35 years increases the risk of macrosomia by 10%.
Previous pregnancies increase the risk of macrosomia because, with each successive pregnancy, the birth weight increases. Longer pregnancies (those beyond the typical 40 weeks) also increase the risk of the baby being macrosomic, especially at 42 weeks and beyond.
Having a boy also increases the chance of macrosomia. Boys are three times more likely to be born macrosomic than girls.
Dangers during childbirth
Babies with macrosomia are more likely to have difficulty moving through the birth canal due to their size.
It is quite common, for example, for the baby’s shoulder to get stuck behind the mother’s pubic bone. The medical term for this is “shoulder dystocia.”
While the baby is trapped, it cannot breathe and the umbilical cord can become compressed. It can also fracture the baby’s clavicle or damage the brachial plexus nerves in the arms; in the most serious cases, this damage can be permanent.
Shoulder dystocia occurs in about 0.7% of all births, but in macrosomic babies the incidence is about 25%.
Mothers are also at increased risk of vaginal tearing during childbirth, which increases the risk of postpartum hemorrhage.
Postpartum hemorrhage is the leading cause of maternal death worldwide, and therefore the larger the baby, the greater the risk of injury during normal vaginal delivery.
Macrosomia in newborns also leads to an increased risk of prolongation of the second stage of labor, which occurs when the cervix is fully dilated and the baby’s head moves into the vagina.
Due to the size of macrosomic babies, this movement can be slower than normal, which can increase the mother’s risk of infection, urinary retention, and hematoma (internal bleeding).
One thing we don’t know about macrosomic babies is whether they stay bigger throughout their lives.
The limited data that exist suggest that they are more likely to be overweight or obese at age 7 and also to develop type 2 diabetes later in life.
We may see more “giant” babies being born, as those born after 1970 seem to weigh around 450g more than newborns before that.
Also, with increasing rates of obesity, which is a major factor in the development of macrosomia, we are likely to see more “giant” babies.
*Adam Taylor is Professor and Director of the Clinical Anatomy Learning Center at Lancaster University, UK.
This article originally appeared on the academic news site The Conversation and is republished here under a Creative Commons license.
It may interest you:
* What is the genetic conflict that is naturally unleashed with pregnancy and why it can cause complications for the fetus and the mother
* The pressure on mothers to return to the body they had before pregnancy
* What are the risks of obesity during pregnancy?
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