Possible Causes Of Slow Fetal Growth

Fetal Growth Restriction: Reasons, Diagnosis And Risks Involved

April 19, 2023

Medically reviewed by Dr. Saritha T Krishnan, MBBS, MD, FAAP

By Dr. Yoga Nagender M, MBBS, MS, MCH


 

Fetal growth restriction (FGR) is a condition in which the baby does not develop to its optimum growth and weight during pregnancy. The common reasons for this condition include high blood pressure of the mother, multiple pregnancies, infections, and consumption of alcohol or smoking during pregnancy. Therefore, it is important to regularly monitor the growth and development of the baby during this period to avoid any complications.

Read on to know about FGR, its causes, symptoms, treatment, and preventive measures.

Different types of IUGRs during pregnancy

There are two main types of intrauterine growth restrictions occurring during pregnancy:

  1. Symmetrical or primary IUGR: The baby has a symmetrical body in proportion with the internal organs, but is smaller than the size of a normal baby of that age.
  1. Asymmetrical or secondary IUGR: The baby has a normal head and brain but a smaller body than what it should be at that gestational age. This condition is not evident until the third trimester.

Reasons For Restricted Growth Of Fetus During Pregnancy

The causes of IUGR are segregated into three broad categories: maternal, fetal and placentali (1).

  • Maternal health is important for the baby to get all the essential nutrients for its growth.
  • Fetal health is necessary to make sure the baby receives the nutrients supplied by the mother.
  • The placenta should be healthy enough to carry the nutrients from the mother to the fetus.

All the factors mentioned below fall into one of the three categories:

  1. Pregnancy-induced hypertension:During pregnancy, your blood pressure is constantly monitored to check for hypertension. An increased blood pressure may indicate hypertensive disorder of pregnancy (gestational hypertension, chronic hypertension preeclampsia). The flow of blood to the placenta is reduced, cutting down on the supply of sufficient oxygen and supplements to the fetus, thereby leading to slow fetal growth (2).


     
  2. Multiple pregnancies: In some cases of multiple pregnancies, the slow fetal development is because of the inefficiency of the placenta to meet the nutritional demands of the multiple babies. Moreover, the chances of hypertensive disorder are also high in multiple pregnancies. IUGR occurs in 25-30% of twin pregnancies (3).
     
  3. Infections:Any infections transferred from the mother during pregnancy can lead to slow fetal growth. Infections such as syphilis (a sexually transmitted bacterial infection), toxoplasmosis (a parasitic infection transmitted mainly through under-cooked meat), cytomegalovirus (viral infection with significant impact during pregnancy due to weaker immunity), and rubella (German measles) increase the chances of IUGR (4).

References:

  1. Parvin Niknafs; (2000); Identification of intrauterine growth restricted babies: development of an IUGR index.
    https://ro.uow.edu.au/cgi/viewcontent.cgi?referer=&httpsredir=1&article=2614&context=theses
  2. S K Srinivas et al.; (2009); Rethinking IUGR in preeclampsia: dependent or independent of maternal hypertension?
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2834367/
  3. Giuseppe Puccio et al.; (2014); Intrauterine growth pattern and birthweight discordance in twin pregnancies: a retrospective study.
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4018970/
  4. Intrauterine Growth Retardation (SGA).
    https://www.magicfoundation.org/downloads/IntrauterineGrowthpdf819.pdf

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