Fetal macrosomia: a big baby

The largest newborn ever to have been recorded weighed over 23 pounds. That baby was born in America in 1897, but died a few hours after entering the world. Still, stories about babies born at around 11 pounds turn up fairly regularly and always inspire awe in any mother hearing about them! Any baby born over 9.92 pounds (4.5 kg) gets the label of macrosomia. Essentially, this means a large baby. What causes fetal macrosomia, and what happens if you are pregnant with a really big baby?

Genetic factors play a big role in determining the size of a fetus (and its later "incarnations"), and it is not a surprise when large parents produce a baby that is larger than usual. Fetal macrosomia, however, mostly occurs as a result of underlying medical conditions. Type 2 diabetes is one rather obvious risk factor for fetal macrosomia.

Gestational diabetes, having given birth to many children already, and obesity are others. Boys are more likely to be really big than girls, and moms who have already had really large infants are more likely to have a baby with fetal macrosomia again.Diagnosis of fetal macrosomia happens through ultrasound or palpation of the uterus. Both these methods can be quite inaccurate; for ultrasounds during pregnancy, an error margin of 300-500 grams should be taken into account. It is, therefore, essential to rely on more than ultrasound to determine if a baby has fetal macrosomia.

Most significantly, prenatal care should include screening and testing for the various types of diabetes.If a pregnant mother has diabetes, or is very obese, treatment or dietary plans can be offered. Beyond that, really large babies will mostly be born through cesarean section. In the case of a truly large baby, c-sections can enable a health delivery, which wouldn't have been possible in the case of a vaginal birth. Women who have been told that they have a "big baby" should remember the error margin and seek second opinions, rather that rushing to have a c-section. Those "big babies" turn out to be 6 pounders quite regularly.