Slow Fetal Growth: Diagnosis, Risks And Possible Reasons

Slow Fetal Growth

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What do we say when people ask us, “Who do you want, a son or a daughter?” Most to-be-moms have just one answer: “Doesn’t matter, I just want a healthy baby.” Isn’t it? The wellness of the fetus is that important for its mother.

Do you know that even after taking proper care during pregnancy the fetus could, sometimes, grow slow? MomJunction tells you about the causes of slow fetal growth, the possible risks, and the preventive measures you can take.

What Is Slow Fetal Growth?

Slow fetal growth is also known as intrauterine growth restriction (IUGR), which is a condition signifying the slow growth of a baby during pregnancy. In this condition, the size of the baby is smaller than the average size at that pregnancy age (1).

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.

IUGR could be the result of certain health issues in the mother.

Reasons For Slow Growth Of Fetus During Pregnancy

The causes of IUGR are segregated into three broad categories: maternal, fetal and placental (2).

  • 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.

[ Read: Things Must Avoid During Pregnancy ]

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

  1.  Preeclampsia: During pregnancy, your blood pressure is constantly monitored to check for preeclampsia (also called as pregnancy-induced hypertension or PIH). An increased blood pressure may indicate preeclampsia, which compresses the veins. Compressed veins restrict the flow of blood to the placenta, cutting down on the supply of sufficient oxygen and supplements to the fetus, thereby leading to slow fetal growth (3).
  1. 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 preeclampsia are also high in multiple pregnancies. IUGR occurs in 25-30% of twin pregnancies (4).
  1. 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 (5).
  1. Lower level of amniotic fluids: It is necessary to have sufficient amniotic fluid in the sac for normal fetal development to happen. However, low fluid level (also termed as oligohydramnios) can lead to fetal growth restriction (6). Various factors, including the health of the mother, certain medications, and a slight rupture of the amniotic sac cause the fluid levels to deplete.
  1. Placental insufficiency: In this condition, the placenta does not work properly. This leads to insufficient supply of oxygen and nutrients to the baby from its mother, resulting in slow growth (7).
  1. Abnormalities of the umbilical cord: The cord connects the fetus with the placenta. It contains one umbilical vein and two umbilical arteries, which carry blood between the fetus and the placenta. However, if there is only one artery in the umbilical cord, then this abnormality leads to fetal growth restriction (8).

[ Read: Umbilical Cord Effects On Pregnancy ]

7. Other maternal and fetal reasons include:

  • the small size of the mother
  • mother’s nutritional intake during pregnancy
  • abnormal shape or size of the womb
  • conditions related to blood vessels such as recurrent bleeding and diabetes mellitus
  • chronic illness in the mother such as sickle cell disease
  • chromosomal abnormalities such as Turner Syndrome and Down Syndrome in the fetus
  • genetic and skeletal abnormalities in the fetus

Slow fetal growth can also occur due to the lifestyle of the mother, such as if she:

  • smokes
  • is underweight
  • drinks alcohol
  • takes drugs
  • follows poor diet
  • is exposed to high doses of radiation or chemicals (11)

During your antenatal checkup, the doctor will measure the fundal height to determine the size of the baby.

Your baby’s size will be monitored throughout the pregnancy, and the measurements will be put on a growth chart. If the doctor finds any abnormality, she does an ultrasound scan to measure the baby’s growth accurately.

Fetal growth measurement is important because slow growth could lead to certain health problems in the baby.

Risks of slow fetal growth (IUGR)

Babies with IUGR have increased chances of getting health issues both before and after birth. The risks include (12), (13):

  • Low birth weight
  • Problems with breathing and feeding
  • Decreased ability to fight infection
  • Hypoglycemia (low blood sugar level)
  • Low Apgar Scores (Apgar score is a test carried out to evaluate the physical condition of the newborn and to determine any immediate need of medical care. The score is determined on a scale of 0 to 2, with 2 being the best)
  • Abnormally high red blood cell count
  • Neurological problems
  • Trouble in maintaining the body temperature
  • Stillbirth

In order to avoid these risks in the baby, the doctor measures the fetal growth regularly when you go for health check-ups.

[ Read: Causes Of Low Birth Weight In Babies ]

How Is Slow Fetal Growth Diagnosed?

The fetal size can be estimated by measuring the fundal height. However, there are other procedures to diagnose IUGR and assess the baby’s health:

  1. Ultrasound: An ultrasound uses sound waves to create images of the baby’s structure and measure its head and abdomen. These measurements are compared with the growth chart to estimate the fetal weight.
  1. Doppler flow: The technique is used to measure the speed and amount of blood flow into the blood vessels of the fetal brain and the umbilical cord, using sound waves.
  1. Weight checks: It is another way of estimating the fetal growth. During every prenatal visit, the doctor will check and record the mother’s weight. If the expecting woman is not gaining appropriate weight, it could result in fetus’ slow growth.
  1. Fetal monitoring: A non-stress test is carried out by placing a sensitive belt around the mother’s abdomen. These belts have transducers attached to an external monitor. The sensors measure the pattern and rate of fetal heartbeat, which gets displayed on the monitor (13).
  1. Amniocentesis: The test involves the collection of a small amount of amniotic fluid through a needle. The fluid sample is tested for any infection or chromosomal abnormality, which can lead to slow growth of fetus (14).

Slow fetal growth can be effectively managed in expecting mothers through regular checkups and healthy lifestyle.

How is IUGR managed?

IUGR is managed based on its severity (15):

  • At stage 0, you are treated as an outpatient with Doppler test done every two weeks. If the results are consistent, your delivery can be at term. But if the Doppler results are abnormal, the fetus moves to Stage I.
  • Stage I, too, requires outpatient care, if you do not have preeclampsia, but you may have to see the doctor twice a week. You could be given antenatal corticosteroids during diagnosis, and you would be done a non-stress testing (NST).
  • In stage II, you have to get admitted as an inpatient as you need to undergo antenatal testing twice a day. If the test results are consistent, then the delivery is recommended at 34 weeks. However, if they are fluctuating, then the healthcare provider might recommend an immediate C-section delivery.
  • In the case of stage III IUGR, delivery is done at 32 weeks gestation.

If your doctor suspects IUGR, then:

  • You will have regular scans to check your baby’s growth. With a Doppler test, the amount of blood flow from the placenta to the fetus is checked.
  • If there is any concern about the fetal growth, your doctor will recommend CTG monitoring, regular scans, and consultant appointments.
  • You will be advised to monitor the movements of your baby closely.
  • If growth restriction is severe, then the doctor may recommend an early delivery by C-section (16) as vaginal delivery would be stressful. In such case, your baby will be put in the neonatal care unit, where it can grow better than inside your womb.

Above all, you need to take care of yourself by eating nutritious food and taking ample rest.

What should you do in the case of IUGR?

Visit your doctor regularly and get carefully checked. Closely monitor your baby’s movement patterns. If your baby does not move very often, contact your doctor and follow their instructions.

Ask your doctor several questions such as,

  • What activities should you avoid?
  • What precautions should you take?
  • What symptoms or problems you should watch out for?

There is little you can do to control IUGR, but certain lifestyle changes could be of help.

[ Read: Nutritional Foods To Eat During Pregnancy ]

How to prevent IUGR?

The below measures can reduce the risk of IUGR:

  • Eat a healthy diet. Healthy foods provide proper nourishment to your baby.
  • Quit smoking and drinking alcohol during pregnancy.
  • Limit the intake of caffeine.
  • Check with your doctor if any medications that you are taking pose a risk of IUGR.
  • Get plenty of rest and keep stress at bay. Try to get at least eight hours of sleep every day.
  • Stay fit by exercising.

Slow fetal growth is not in your hands. But what you can do is have a healthy lifestyle, exercise and keep away from unhealthy habits such as smoking. Talk to your doctor and follow their instructions. If the fetal growth is still slow, all you can do is wait for the baby to come out of your womb. Breastfeeding and careful nurturing could help you do the damage control.

Have an experience to share? Leave a comment below.

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shreeja pillai

Postgraduate in Chemistry and content writer. She has worked as a research analyst with a leading multinational pharmaceutical company and also holds a diploma in pharmaceutical regulatory affairs. Her interest in the field of medical research has developed her passion for writing research-based articles. She is a writer for MomJunction and aims at providing informative articles based on health and wellness. Apart from writing, she takes a great interest in music and traveling. know more about her at
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