Macrosomia (Big Baby Syndrome) – Causes, Symptoms, Treatment, Risk Factors

Macrosomia can be described in common terms as “big baby”. Any baby that is larger in size than the average ones are called as big baby. Macrosomia babies weigh more than 8 pounds by birth and statistics report that about 9% of babies are born with Big Baby Syndrome or Macrosomia worldwide. Giving birth to a big sized baby poses risk for the mother during the time of delivery. Further it can cause health problems for the child as he grows giving rise to diabetes and obesity related problems.

Signs and Symptoms :

  • Big babies grow in the womb like other babies and it is not possible to detect macrosomia during the term of pregnancy.
  • Certain cues can suggest that you may be having macrosomia babies. Fundal height measurement can indicate the baby can be big one. Fundal height is the distance between the pubic bone and the top of your womb (uterus). Big babies are likely to produce more output of urine than normal ones. Excess of amniotic fluid suggests that the baby’s urine output is more and it can be big baby.

Macrosomia Causes :

There is no specific cause for having macrosomia babies. It can be due to genetic factors or can be due to predisposed obesity of the mother. In some families fetal macrosomia runs in family and such mothers are at high risk of having big baby. In rare cases growing infants can develop medical problems causing macrosomic babies.

Risk Factors :

  1. Any mother can give birth to big baby irrespective of age. But certain factors given below increase the risk of macrosomia babies.
  2. Prolonged Diabetes : Women with diabetes for long duration before pregnancy or having uncontrolled diabetes is at risk of having fetal macrosomia.
  3. Obesity : Women who are already obese before pregnancy and those with history of fetal macrosomia have increase chance of having big sized babies.
  4. Age : Women who are getting conceived after 35 years are at risk of fetal macrosomia.
  5. Other risk factors of macrosomia include increasing number of pregnancy (more child-births), overdue pregnancy (continuing pregnancy after due date) and having a boy baby.


Complications :

Macrosomia can cause problems both for the mother (at the time of delivery) and the infant. It can cause maternal complications like injuring the birth canal (due to overweight), labor problems, and heavy bleeding after delivery. The infant may not be able to push through the opening of the vagina requiring C-section delivery or using forceps for pulling the baby.

The infant can tear the delicate vaginal tissues causing genital tract lacerations. Further the uterine muscles may not contract properly as before causing unwanted increased bleeding to the mother. The babies with fetal macrosomia have increased chance of developing low blood sugar levels. Such babies are more likely to develop childhood obesity than others. Further such babies are at risk of metabolic syndrome causing various medical problems like high blood pressure, excess of body fat and high cholesterol posing risk of cardiac disease.

Tests :

It is not possible for detecting macrosomia babies during the stage of pregnancy. Baby’s actual weight can be assessed only after birth. In many cases the due date is misguided predicting the baby is very large for his gestational age. Ultrasound scan can be done to get estimation of the size of the baby and his body parts. Antenatal test can be done to check the baby’s heart rate and his movements. Non-stress test can help in detecting the baby’s profile to the extent possible.

Macrosomia Treatment :

  • Nothing can be done to prevent macrosomia since things are out of control.
  • In case your health care provider diagnose the baby is large he/she may consider for C-section delivery to avoid any birth-time complications for the mother and the infant.
  • Women with diabetes and obesity problem are considered for surgical delivery.
  • Babies whose weight is found to be more than 9 pounds before delivery are delivered with the option of C-section rather than normal delivery to prevent any complications.
  • Surgical delivery is considered for shoulder dystocia cases wherein the shoulder of the infant would get stuck with the pelvic bones.
  • Often macrosomia babies would not develop birth-time problems excepting few minor injuries.
  • As the baby grows, his/her health condition is monitored for blood sugar levels and weight related issues.
  • Childhood obesity is the common problem faced by such babies for whom suitable medications combined with exercises and diet is recommended.

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