Big baby syndrome – what are the risks?

Giving birth to a big baby is medically known as macrosomia. Usually, if the parents are bigger than average, the mother will give birth to a big baby. However, there are other factors that are known to cause a baby to be large, such as obesity and gestational diabetes.

A big baby is classed as weighing more than 4kg at birth, but this does vary slightly depending on your doctor. Doctors can normally determine if the baby is larger than average when still inside the womb through measurements taken during ultrasounds.

Factors that contribute to giving birth to a big baby

  • Mothers who have diabetes or gestational diabetes
  • Excessive weight gain during pregnancy
  • Obesity
  • Diet high in sugar and fat

If you have previously given birth to a big baby during your first pregnancy, there is a high chance that you may carry larger babies in future pregnancies. In addition, your baby’s gender can play a part. Boys are likely to be bigger than girls at birth.

RELATED: The complete guide to labour and delivery

How common is giving birth to a big baby?

About 1 in 10 babies born are considered to be a macrosomia birth. Despite the list of risk factors, doctors are still relatively uncertain about the causes of a big baby. In some cases, women who are at high risk have been known to deliver a baby of average size. In contrast,  there is a big proportion of low risk women who deliver a baby weighing more than 4kg.

Giving birth to a big baby carries risks during a vaginal delivery, but most macrosomia births are not life-threatening to the mother or baby. For the safety of both mother and baby, your gynaecologist may suggest a C-section.

What are the complications of a vaginal delivery when it comes to a big baby? More details on the next page…