8 Possible Causes of Slow Fetal Growth

6 min read

Written by Editorial Team

Editorial Team

Possible Causes of Slow Fetal Growth

Pregnant women are proud of their growing bellies. The general belief is that the size of a growing belly indicates the size of the growing fetus. But you will be surprised to know that the belly size doesn’t always correspond to the baby size. The term IUGR refers to when a fetus in the womb (a baby) does not grow as expected. Babies who are smaller than the number of weeks of gestational age are said to be small for gestational age. In this article, we take a closer look at the causes of slow fetal growth and the main ways to identify IUGR.

A baby’s size is influenced by his or her parents’ sizes. However, the large majority of women who have a baby that is small for gestational age have problems with their child’s growth during pregnancy. They suffer from nutritional and oxygen deficiency. The issue can arise at any stage of pregnancy.

In This Article

What is Slow Fetal Growth?

Slow fetal growth, widely known as intrauterine growth restriction (IUGR) is a condition where a baby grows at a slower pace when compared to a normal baby while in the mother’s womb. The baby’s weight is lesser than it ought to when compared with a normal growing baby in the same gestational period.

An infant’s development and weight are imperative. Slow fetal growth will result in babies with low birth weight. Babies with low weight will probably have issues close to the delivery or immediately after delivery. Truth be told, 60% of neonatal deaths (the death of newborns within the first 28 days after birth) happen due to low birth weight, which is an immediate result of slow fetal growth.

How Many Types of IUGRs are There?

There are two types of growth retardation:

1. Symmetrical or Primary Intrauterine Growth Retardation

The fetus will have a typically proportioned body and internal organs but is less in size than other fetuses of the same gestational age. This type of IUGR is responsible for around 25% of all incidents of slow fetal growth.

2. Asymmetrical or Secondary Intrauterine Growth Retardation

The fetus will have a normal-sized head. Be the body is much less in size than it ought to be. On an ultrasound, their head gives off the impression of being much bigger than their body.

What are the Symptoms of Slow Fetal Growth?

The main symptom can be that the mother is not putting on as much weight as expected. Your doctor may find that your uterus is smaller than anticipated for your phase of pregnancy. In addition, lower amniotic fluid levels can also indicate an IUGR. Most doctors confirm this condition with the help of ultrasounds.

How is Slow Fetal Growth Diagnosed?

An ultrasound scan is the best way to diagnose slow fetal growth. In early pregnancy, a fetus size smaller than normal might be no reason for worry. Some women are uncertain of their last menstrual period. In this manner, the fetus’s gestational age may not be precise. The baby may look small when it’s really the right size.

Once the doctor suspects IUGR during early pregnancy, they will monitor fetal development continually through ultrasounds. If the fetus is unsuccessful in achieving normal growth (by taking the measurement of fundal length and by examining whether it coincides with the age of pregnancy), the doctor will confirm IUGR.

What are the Possible Causes of Slow Fetal Growth?

IUGR happens for various reasons and can begin at any phase of pregnancy. There are various components that increase the fetus’s IUGR risks.

  • Maternal Reasons: Any underlying health conditions in the mother or lack of proper nutrition can cause this condition in the fetus
  • Fetal Reasons: Chromosome abnormalities, defects in the fetus, or any infections also can contribute to slow fetal growth.
  • Multiple Gestations: A twin or triplet pregnancy can also result in the fetus having low weight.
  • Uterine/Placental Reasons: Sometimes, additional uterine reasons such as an unfavorable environment or lack of passing of nutrition can also cause slow fetal growth.

[Read: Placenta Accreta – Pregnancy Complication]

8 Possible Causes of Slow Fetal Growth

Causes of Slow Fetal Growth

Here are eight possible reasons that slow down fetal growth.

1. Poor Lifestyle Habits of Mother

The mother’s lifestyle habits majorly influence the growth and development of the fetus, according to news research studies. If a mother does not have proper nutritional habits, it can have a negative impact on the fetus. Researches signify the diet and lifestyle habits of the mother such as smoking, drinking, drug abuse, improper eating habits, and not taking the required folic acid supplements can cause slow fetal development.

2. Pre-Eclampsia

Do you know the reason for your blood pressure being checked during your routine checkups? This is because high blood pressure in pregnant women can lead to preeclampsia or pregnancy-induced hypertension (PIH). Preeclampsia causes the veins to compress. This will restrict the blood flow to the placenta and affect the growth of the fetus. The developing infant gets less oxygen and low nutrition, which ultimately leads to slow fetal growth.

[Read: Preeclampsia – Causes, Symptoms, Risk Factors, Treatment]

3. Infections

When the fetus gets exposed to the infections passed from the mother, the chances of slow fetal growth increase. Such infections include:

  • Syphilis (sexually transmitted bacterial infection)
  • Cytomegalovirus (viral infection, which has a significant impact when the immunity is weak, as during pregnancy)
  • Toxoplasmosis (infection with a parasite transmitted mainly through under-cooked meat somewhat pass unnoticed by the mother, but cause harm to the fetus), and
  • Rubella also called German measles

4. Multiple Pregnancies

multiple pregnancies

Multiple pregnancies develop at around the same rate as single pregnancies up to a specific point. The development rate of multiple pregnancies starts to slow eventually as the placenta can’t deal with any more development on the grounds that the children go head-to-head for nutrients. Likewise, twin pregnancies are twice as liable to create preeclampsia as single pregnancies and half of the triplet pregnancies are found to create pre-eclampsia.

5. Placental Insufficiency

Placental insufficiency is a condition when the placenta does not work properly as it should, resulting in the fetus getting less oxygen and nutrients from the mother. Obviously, this will lead to slow fetal growth.

6. Chromosomal Abnormalities

Chromosomal variations from the norm are the most common reasons for birth defects, therefore slowing down the fetal growth. Congenital abnormalities can also cause the baby not to grow properly.

7. Low Level of Amniotic Fluids

An optimum level of amniotic fluid is required for normal fetal development. The level of amniotic fluid can fall below normal (oligohydramnios) due to various reasons mother’s medications, health conditions, placenta abruption, a slight rupture in the amniotic sac, etc. This will slow down fetal growth.

8. Umbilical Cord Abnormalities

The umbilical cord is a long tube-like structure connecting the fetus with the placenta of the mother. It carries oxygen and nutrients from the mother’s body (placenta) to the fetus. The umbilical cord typically contains two umbilical arteries and one umbilical vein, which carry blood between the placenta and the unborn child. Sometimes, the umbilical cord contains only one artery and can result in slow fetal growth.

How Can I Prevent Slow Fetal Growth?

Some causes of IUGR are beyond your control and there is little that you can do. The first thing to do is to follow your doctor’s advice to the ‘T’, and eliminate the causes of slow fetal growth in your control. Leading a healthy lifestyle, staying away from stress, getting regular exercise, sleep and rest, and eating a well-balanced healthy diet are some measures that you can yourself take to avoid slow fetal growth.

[Read: Baby On Board? A Healthy Lifestyle Can Help Prevent Birth Defects]


1. How do I Know My Fetus is Not Growing Properly?

Doctors prescribe scans at regular intervals. The growth is compared between scans. The professionals can tell you about the growth.

2. Can My Weight Indicate Fetal Growth?

Yes, it can. It’s one of the main indicators. If you are not gaining enough weight, it can mean the baby is not growing well.

3. Can High Blood Pressure in Pregnant Mother Affect Baby’s Growth?

Yes, it can. As pressure increases, the blood flow can be compromised. This in turn will affect blood reaching the baby.

4. Why Do My Twins Weight Low?

Multiple pregnancies will lead to low baby weight. The fetal growth rate will also be, low. The space and nutrients are all shared, so it will be low.

Read Also: 10 Potential Complications With Twin/Multiple Pregnancies

Editorial Team,

With a rich experience in pregnancy and parenting, our team of experts create insightful, well-curated, and easy-to-read content for our to-be-parents and parents at all stages of parenting.Read more.

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