I gave birth two days ago,contrary to my understanding and expectation, my baby weighed smaller than my first child (3.7kg versus 2.65kg). What could have been the cause of this and are there any later consequences of this?

Emobileclinic Member: I gave birth two days ago, contrary to my understanding and expectation, my baby  weighed smaller than my  first child (3.7kg versus 2.65kg). What could have been the cause of this and are there any later consequences of this?

Doctor Response

Congratulations on the birth of your child. There are a wide variety of reasons why a baby may be born small and these includes chromosomal abnormalities, fetal infections and congenital abnormalities. However, most babies that are born small are either constitutionally small (i.e. healthy but born to small parents and fulfilling their genetic growth potential) or are small due to abnormal placental function and have fetal growth restriction (FGR).

Fetal growth restriction is a major cause of morbidity and mortality amongst neonates and infants, and the cost associated with providing adequate facilities to look after these babies is significant.

FGR is defined as a failure of a fetus to achieve its genetic growth potential resulting usually, in a fetus that is small for gestational age (SGA). SGA means that the weight of the fetus is less than the tenth centile for its gestation. The term SGA and FGR are not synonymous. Most SGA fetuses are constitutionally small and not compromised. Contrary, Intrauterine growth restriction (IUGR) indicates that there is a disease process inhibiting the growth rate of the fetus. Consequently, some FGR fetuses may not actually be SGA, but nevertheless will have failed to fulfil their growth potential.

Common causes of fetal growth restriction include aneuploidies such trisomy 18, structural abnormalities e.g. renal agenesis and intrauterine infections such as toxoplasmosis and cytomegalovirus. Others include maternal under-nutrition resulting from poverty and eating disorders; maternal hypoxia e.g. living at altitude and cyanotic heart disease; drugs e.g. alcohol, cigarettes and cocaine; factors that reduce uteroplacental perfusion such as multiple pregnancy, sickle cell disease and inadequate trophoblastic invasion as well as factors that reduces fetoplacental perfusion e.g. single umbilical artery and twin-twin transfusion. History of FGR in previous pregnancy is also a risk factor for FGR.

The prognosis of FGR is highly dependent on cause, severity and the gestational age at delivery. When FGR is related to a congenital infection or chromosomal abnormality, subsequent development of the child will be determined by the precise abnormality. Of babies with FGR due to uteroplacental insufficiency, some babies will suffer morbidity or mortality as a result of prematurity. For the survivors, the long term prognosis is good with low incidences of mental and physical disability and most infants demonstrate ‘catch-up growth’ after delivery when feeding is established.

A link between FGR and adult onset of hypertension and diabetes has been established. It remains to be seen whether other associations will be found in future.

Responded By

Dr. Nkem; Consultant Obstetrician & Gynecologist